IIHF INTERNATIONAL ICE HOCKEY FEDERATIONIIHF GUIDETO SUSTAINABLE
ICE ARENAS© IIHF 03/2023

IIHF GUIDE TO SUSTAINABLE ICE ARENAS 2022

2

SUMMARY

The aim of this document is to give a general technical overview of the specifics of ice arenas and their technicalsystems. Special attention is directed to the functions that use energy, since the overall aim is to give the readers
ideas on how to successfully save energy in their own arena.
Initially the key aspects and meaning of “sustainable ice arena technology” must be defined and the word “sustainable” literally means “able to be upheld at a certain level”. This indicates something that is robust and may be maintained long-term without a problem, thus for ice rinks sustainability generally leads to two areas of focus: Functions andResources. From a reader perspective it should be understood that sustainable ice rink technologies consist of longterm solutions that lead to optimum function in a way that manages resources efficiently.
Further, this guide discusses passive and active functionality in the ice arena where the “passive” part refers to the“building structure” and its particular properties. Secondly, the “active” functionality covers the energy systems thatwork together to maintain the ice, temper the arena room, dehumidify the indoor air, etc.
The process to achieve sustainability should always be based on hard technical facts. The ambition in thisguide is to base the presented technical arguments and solutions on a scientific background and context; therefore, the guide has an extensive list of references where many are different scientific papers andreports. An unbiased and scientific base is key for best practice and thus it should be viewed as a cornerstone
in this guide.
This guide also covers softer factors such as the process to procure the technical upgrades and retrofits
necessary to achieve the desired results. Again, the importance of an impartial perspective to achieve the best
results is stressed. Therefore, it is recommended for the arena owner to consult competent neutral players, atleast in the prestudy and specification processes, to receive an unbiased and vendor neutral view on the planned
measures.
Lastly, improving the energy efficiency of an ice arena, not the least by optimizing heat recovery from the refrigeration system, is one of the most important ways to make the facility more sustainable. In most cases this also implies
that the ice rink owner benefits from an increased economic performance of the facility.

Updated version 2023-03-29.

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TABLE OF CONTENT

1BACKGROUND

8

1.1.
1.2.

Objective. . ...............................................................................................................................8
Authors. . .................................................................................................................................82

INTRODUCTION TO SUSTAINABLE ICE ARENA TECHNOLOGY

2.1.
2.2.
2.3.
2.4.
2.5.

What is sustainable ice arena technology?..................................................................................9
Passive and Active management of ice arena conditions............................................................. 11
The Big Five energy systems .................................................................................................. 12
Savings potential in ice arenas................................................................................................ 14
Environmental impact of technical solutions.............................................................................. 18

3

BUILDING AND RETROFITTING ICE RINKS –SUSTAINABLE WORKING PROCESSES

3.1.
3.2.

Consulting an impartial industry expert .................................................................................... 20
Retrofits . . ............................................................................................................................. 22

4

SUSTAINABLE BUILDING ENVELOPE

4.1.
4.2.

Envelope – Roof and wall constructions.................................................................................... 24
Climate zones. . ...................................................................................................................... 28

5

SUSTAINABLE RINK FLOORS

5.1.
5.2.
5.3.
5.4.

Structure. . ............................................................................................................................. 30
Rink pipes............................................................................................................................. 32
Subfloor heating / Freeze protection.. ....................................................................................... 33
Dasher boards....................................................................................................................... 34

6

SUSTAINABLE ENERGY SYSTEMS

6.1.
6.2.
6.3.
6.4.
6.5.
6.6.

Refrigeration system.. ............................................................................................................. 35
Heating systems.................................................................................................................... 50
Arena room dehumidification................................................................................................... 54
Air handling. . ......................................................................................................................... 58
Arena room lighting. . .............................................................................................................. 62
Building and energy system management ................................................................................ 65

9

20

24

30

35

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TABLE OF CONTENT7SUSTAINABLE WATER MANAGEMENT

7.1.

Resurfacing water recycling.................................................................................................... 68

8

CASE STUDIES

8.1.
8.2.

Facility case studies............................................................................................................... 70
Function case studies............................................................................................................. 76

9

QUICK SAVINGS IN EXISTING ICE ARENAS –

10

67
70

NO/LOW INVESTMENT

79

REFERENCES

80

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TABLE OF FIGURES

Figure 1.
Figure 2.

Figure 3.
Figure 4.
Figure 5.

Figure 6.

Figure 7.
Figure 8.
Figure 9.
Figure 10.

Figure 11.
Figure 12.
Figure 13.
Figure 14.
Figure 15.

Figure 16.
Figure 17
Figure 18.
Figure 19.

A sustainable ice arena consists of long-term solutions that lead to optimum function
in a way that manages resources efficiently... ..............................................................................9
A well-functioning ice arena must be able to handle the complex heat loads and moisture loads
that come along with this specific environment. In this picture they are not well managed,
causing foggy conditions.. . ...................................................................................................... 12
Indoor ice rink energy systems – The big five............................................................................ 13
Main energy uses in a typical/conventional ice rink in Sweden with inefficient and efficientenergy technologies (Stoppsladd, 2014; ASHRAE, 2017)... .......................................................... 14
Comparison of energy performance in Nordic ice rinks. The shown values reflect the
average amount of purchased energy (electricity and any other potential heat source)
during a day of ice arena activity... ........................................................................................... 16
Life-cycle cost results for sustainable energy solutions (alternative 1 & 2) in an ice rinkcompared to existing system. The results show that investing in long-term solutions will yield
the biggest savings for the ice rink owner................................................................................. 17
The Antarctic ozone hole on September 16 in the years 1979 and 2011
(NASA Earth Observatory, 2012).............................................................................................. 18
History and future of refrigerants divided in 4 generations (Makhnatch, 2018)... ............................ 19
The procurement process contains many pitfalls, which mainly occur due to the lackof knowledge, and may lead to low quality results and/or significant waste of money..................... 21
An impartial industry expert can support the ice rink owner in investigating, designing,and specifying the optimum system solution in procurement documents. Tenders will as result
be comparable in terms of quality, and the client will get the best possible solution to coverdemands for the lowest price... ................................................................................................ 21
Ice arena with wooden material elements in the building envelope............................................... 24
Stack effect in an ice rink depending on a time of a year (Rakennustieto, 2007).. .......................... 25
Air leakage traces near the joint between roof and wall.............................................................. 26
Polyethylene self adhering air barrier (Delta Vent, 2019)............................................................. 27
Open doors either directly towards outdoors, or between comfort and arena zone causesignificant energy and moisture influx into the arena room. In addition, basic uninsulated wooden
doors are found between climate zones in some ice rinks which is not an optimal solution............. 29
Doors between the cold space and heated spaces must be with high thermal resistance,
hermetically sealed and normally kept close.............................................................................. 30
Typical layout of and ice rink floor (ASHRAE Refrigeration, 2014)................................................. 31
Typical piping layout in Europe with headers on the one short end side........................................ 32
Two different header arrangements: conventional (left) and reversed return (right),

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TABLE OF FIGURES

Figure 20.
Figure 21.
Figure 22.
Figure 23.
Figure 24.
Figure 25.
Figure 26.
Figure 27
Figure 28.
Figure 29.
Figure 30.
Figure 31.
Figure 32.
Figure 33.
Figure 34.
Figure 35.
Figure 36.
Figure 37.
Figure 38.
Figure 39.
Figure 40.
Figure 41.
Figure 42.

where the latter is generally recommended............................................................................... 33
Principle solution on freeze protection distribution below the rink floor......................................... 34
Dasher boards fulfil important functions, not the least in terms of safety... .................................... 35
The primary system (on the left) involves a primary refrigerant, it cools a fluid in a secondary
system (on the right) that circulates in the rink pipes... ............................................................... 36
Two main refrigeration system configurations in ice rinks, simplified schematic... .......................... 37
The global tendency is to “return to the roots” and select natural refrigerants (Danfoss)................. 40
Energy balance in a Nordic training ice rink with 8-month season................................................ 41
The refrigeration system usually releases more heat than what a typical ice rink needs.
It is therefore interesting to look for heating demands beyond an ice rink..................................... 41
The first CO2 primary refrigerant system in ice rink in Europe was installed in 2014 in Gimo,
Sweden. Picture source: Google maps...................................................................................... 42
Principle of a CO2 indirect to the left and CO2 DX to the right, with heat recovery......................... 43
Overview of a CO2 DX refrigeration system in an ice rink............................................................ 44
A modern fully indirect NH3 refrigeration system....................................................................... 45
Thermophysical properties of discussed secondary refrigerants at -10°C
having freezing points of -20°C (Kilberg, 2020)......................................................................... 46
Summary about main advantages and disadvantages with the most common
secondary fluids in ice rinks.................................................................................................... 47
CO2 receiver in a large ice arena where CO2 is circulated in the rink piping................................. 48
Required pump size difference between CaCl2 pump (on the left) and NH4OH pump(on the right), for the same cooling capacity of 250 kW at -10/-8°C............................................ 49
Ice rinks are heating intensive facilities with many demands....................................................... 50
Heat recovery from modern refrigeration makes such systems a 2-in-1 solutions
as they provide both cooling and heating.................................................................................. 52
Groups of accumulator tanks with coils for tap water pre- and post- heating... .............................. 53
Principle overview of a refrigeration and heat recovery system (Illustration by EKA)... ..................... 53
Moisture problems are known in many ice rinks. Solution to keep the indoor humidity
at acceptable level must be used............................................................................................. 54
The working principle of a sorption type of dehumidifier (left) and unit (right)................................ 55
The working principle of a refrigeration type of dehumidifier... ..................................................... 55
Sorption based dehumidification that utilizes the heat recovery from refrigeration,referred to as Generation 2..................................................................................................... 56

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TABLE OF FIGURES

Figure 43.
Figure 44.
Figure 45.
Figure 46.
Figure 47.
Figure 48.
Figure 49.
Figure 50.
Figure 51.
Figure 52.
Figure 53.
Figure 54.
Figure 55.
Figure 56.
Figure 57.
Figure 58.
Figure 59.
Figure 60.

Comparison of energy use between control strategies based on relative humidityand dewpoint/absolute humidity in two ice rinks........................................................................ 57
Application of recovered heat from a modern refrigeration system in the reactivation processleads to energy savings of ca 40% in Gen 1 and 85% in Gen 2 sorption dehumidifiers... ................ 58
Air supplied to different zones in ice arena: Dehumidified air above the ice, and heated air
towards the stands. Fresh air intake only when necessary... ........................................................ 58
The ventilation and dehumidification distribution systems should be separated... ........................... 59
Textile ducts in an ice rink where dry air is distributed over the ice and “comfort air”
to the stands......................................................................................................................... 60
Example of a principle AHU solution for arena room (IV Produkt, 2022)......................................... 60
Example of a central air handling unit in an ice arena, the unit is located in a technical room... ....... 61
Measured CO2-levels in a typical Nordic ice rink operating on full air recirculation........................ 62
Example of an ice rink with a light tube installation.................................................................... 63
Efficiency of different lighting types during their lifespan............................................................ 63
An ice rink with a modern LED-lighting system.......................................................................... 64
The control system overview in an ice rink showing the lighting control signal, power and energy.. . . 66
Screenshot from an ice rink online monitoring system that includes 1 main and 6 submetersof both heat and electricity. It allows to analyse and optimize the systems with high accuracy......... 66
Resurfacing water account for approximately 1 mil litres per year and ice sheet............................ 67
By recycling the resurfacing water from the melting pit, the water management of anice arena can be significantly improved.................................................................................... 68
Classic melting pit function without water recycling... ................................................................. 69
Water recycling applied in melting pit function... ........................................................................ 70
Quick savings can often be achieved in existing ice arenas by adjusting
and/or optimizing the operation of existing solutions.................................................................. 79

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FRAMEWORK1BACKGROUND

1.1.

OBJECTIVE

The scope and objective of this document is to give a general and not too deep technical overview of the specifics
of ice arenas and their technical systems. Special attention is directed to the technical functions that use energy in
one way or another, since the overall aim is to give the readers ideas as to how to successfully save energy in theirown arena.

1.2.

AUTHORS

EKA – Energi & Kylanalys AB
Prästgårdsgränd 4
125 44 Älvsjö, Sweden
Tel. +46 8-550 102 10
www.ekanalys.se
EKA (Energi & Kylanalys) consists of specialists in the field of refrigeration, energy analysis, energy efficiency andbuilding physics in ice arenas in particular.
EKA’s core competence lies in refrigeration engineering with a focus on natural refrigerants. Past projects include
Europe’s first full CO2 ice arena which became self-sufficient on its own heat recovery system. As an impartial expert in the field of sustainable energy and especially ice rinks, EKA is of service to both private and public sectors
worldwide.
EKA has developed and possesses a bank of technical information and experience developed during its activity
in the refrigeration and ice arena industry since 2004. EKA’s designs are based on a combination of accumulated
experience and field data, which are implemented in energy calculations that are done with publicly available softwares. These tools, methods and results have to a large extent been peer reviewed by the research community inthe industry in scientific articles and academic conferences.
EKA provides a wide range of services in refrigeration and other ice arena technologies. The general idea is that as
an industry expert, EKA can support and, if necessary, also represent the client with the necessary knowledge in theprocess of developing and realise the best system solution.
The following people have contributed to the creation of this report:•
Jörgen Rogstam
EKA – Energi & Kylanalys•
Juris Pomerancevs
EKA Baltic•
Cajus Grönqvist
EKA Finland

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FIELD OF ACTIONTECHNOLOGY••

Simon Bolteau EKA – Energi & Kylanalys
Yingrui Hao
EKA – Energi & Kylanalys

2

INTRODUCTION TO SUSTAINABLE ICE ARENA TECHNOLOGY

2.1.

WHAT IS SUSTAINABLE ICE ARENA TECHNOLOGY?

Before introducing the key aspects of sustainable ice arena technology, an understandable question that may arise
to the reader is: what is really meant by the word Sustainable?
The word sustainable literally means “able to be upheld at a certain level”, indicating something that is robust
and can be maintained the way it is on the long-term without problem. From a building management point of view,
reaching sustainability generally leads to two areas of focus: Functions and Resources, where the latter are used toachieve the previous.
These two elements of sustainability are listed below along with some examples from the ice arena technology
perspective. While the examples listed below could be expanded further considerably, the most important thing toremember from the reader perspective is that sustainable ice rink technology consists of long-term solutions thatlead to optimum function in a way that manages resources efficiently.

Figure 1.

A sustainable ice arena consists of long-term solutions that lead to optimum function in a way that manages resources efficiently.

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IIHF GUIDE TO SUSTAINABLE ICE ARENAS 2022

FIELD OF ACTIONTECHNOLOGY

A Sustainable Ice Arena involves Sustainable:
1.
a.

Functions, e.g.:
Ice arena specific functionsi.
Ice qualityii.
Lighting conditionsiii.
Heat load management		1.
Minimize unnecessary loads on ice sheet
iv.
Moisture load management		1.
Minimize unnecessary loads in arena roomb.
Visitor comforti.
Temperature levelsii.
Indoor air qualityiii.
Air and heat distributionc.
Structural integrity & healthi.
Load bearing capabilities
ii.
Moisture handling		
1.
Dehumidification control		2.
Zonal Air managementiii.
Moisture safe building envelope designd.
Visitor safetyi.
During hockey / ice skating activities in generalii.
In case of:
		 1.
Fire
		
2.
Refrigerant leaks
These are of course just a selection of many functional requirements a good ice arena needs to comply with.
2.
a.

Resources, e.g.:
Technical propertiesi.
Building materials
ii.
Refrigeration system		
1.
Refrigerant and other fluid typesiii.
Heating sourcesiv.
Dehumidifier type

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IIHF GUIDE TO SUSTAINABLE ICE ARENAS 2022

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FIELD OF ACTION
CONDITIONSb.

c.

Energy type & its use for:i.
Coolingii.
Heatingiii.
Dehumidification
iv.
Ventilationv.
Lightingvi.
Misc.
Water usage

Now that the sustainable ice arena has been defined within the context of this guide, the next step is to look at the
key aspects of sustainable ice rink technology that should be understood by an ice rink owner, and which will be themain focal points when discussing sustainable solutions in this guide.

2.2.

PASSIVE AND ACTIVE MANAGEMENT OF ICE ARENA CONDITIONS

An ice arena is a building with particular conditions: Within the same arena room there is an ice sheet that needs tostay frozen, while there generally also are heating and air quality demands for visitor comfort. Furthermore, these
conditions often result in a special challenge, where the air humidity in the arena room may become too high andneeds to be controlled to avoid problems, such as damage to structures. Last but not least, the space should also
be well illuminated for comfort and safety reasons.
A well-functioning ice arena must be able to handle the complex heat loads and moisture loads that come alongwith the abovementioned type of environment. This leads to two areas of focus:
1.
2.

The Building Structuresa.
To passively manage the heat and moisture loads in the ice arena
The Energy Systemsa.
To actively manage the heat and moisture loads in the ice arena

Sustainable building structures, such as the building envelope, will be treated in this guide. However, Improving theenergy efficiency of the ice arena is one of the most important ways to make the facility more sustainable, andfor the benefit of the ice rink owner it will often also increase the economic performance of the facility.

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IIHF GUIDE TO SUSTAINABLE ICE ARENAS 2022

FIELD OF ACTION
ENERGY SYSTEMS

Figure 2.

A well-functioning ice arena must be able to handle the complex heat loads and moisture loads that come alongwith this specific environment. In this picture they are not well managed, causing foggy conditions.

2.3.

THE BIG FIVE ENERGY SYSTEMSTo operate an ice arena there are generally five basic energy systems required:
•
•

•
•
•

Refrigeration
To manage the heat loads on the ice sheet
HeatingSpace heating
Hot water
Dehumidification
To manage the humidity level in the arena room
Ventilation
When necessary, to maintain air quality
Lighting
To maintain lighting conditions

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IIHF GUIDE TO SUSTAINABLE ICE ARENAS 2022

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FIELD OF ACTION
ENERGY SYSTEMS

These systems are here referred to as the “big five” because they typically account for more than 90% of the energy
used in the ice rink. In the Figure below these energy systems are schematically indicated in the ice rink.

Figure 3.

Indoor ice rink energy systems – The big five.

The big five energy systems are present in essentially every ice rink – big or small – as will be covered many times
in this guide. Further, these systems interact – regardless of, if you want it or not. By connecting these systems in asensible way there are great energy savings to profit from. When looking at the picture above it is evident that theheat supplied in the ice rinks space will affect the ice. In fact, an indoor ice rink space is nothing but a thermal short
cut with 1800 m2 ice surface which cools the space. At the same time, we want to provide thermal comfort for users
and spectators by supplying heat by means of warm air, radiators or floor heating. The warmer the air the larger
are the “short cut” losses, which results in higher demand for cooling on the refrigeration system side. Lighting anddehumidification also affect indoor climate and the heat transfer to the ice, which again takes to the conclusion thatall systems interact. Interconnecting and controlling these systems together makes a whole lot of sense.

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FIELD OF ACTIONSAVINGS POTENTIAL

To further illustrate the significance of the five main energy systems, Figure 4 is shown. Results from investigations
suggest that in conventional ice arenas refrigeration contributes to the largestIIHF
portionwithtoaround
43% andGuide
sustainable
ice heating
arenasdemands come next with around 26%. The other functions are estimated with up to a 10% share each.
2022
Purchased energy breakdown
in a typical ice rink withinefficient energy technologies

6%

Purchased energy breakdown
in a typical ice rink withefficient energy technologies

6%22%

Refrigeration

9%
43%
10%

HeatingLighting

9%
4%

65%

Ventilation/Fans
Dehumidification
26%

Misc.

Total energy use
1000 MWh/year

Total energy use
460 MWh/year*Ventilation includes Misc.
in this chart

Figure 4. Main energy uses in a typical/conventional ice rink in Sweden with inefficient and efficient energy technologies
Main energy uses in a typical/conventional ice rink in Sweden with inefficient and efficient energy technologies(Stoppsladd, 2014; ASHRAE, 2017).

Figure 4.

(Stoppsladd, 2014; ASHRAE, 2017).

In modern ice arenas with efficient system solutions the relations between energy demands are a bit
different,
the efficientright in the
Figureabove,thebutrelations
the conclusion
theIn
modern as
iceshown
arenastowith
systemsolutions
betweenremains
energy neverthelessdemands are thea bitsame:different,
bigshown
five energy
that
are emphasized
are of crucial
and
when
as
to the systems
right in the
Figureabove, but thehere
conclusion
remainsimportanceneverthelesstheshould
same: bethethebigfocus
five energy
it comesthat
to improving
energyhere
efficiency
in ice rinks.
systemsare emphasized
are of crucial
importance and should be the focus when it comes to improving energy efficiency in ice rinks.
The biggest energy savings potential is often to cover the heating demands with recovered heat from therefrigeration
system,with potential
the possibility
the purchased
heatingenergyheat
demandas indicatedThebiggest energy
savings
is oftenoftoeliminating
cover the heating
demands withrecoveredfrom therefrigerain Figure
4, withand thiswill be further
discussedthe
later
on in theguide.energy demand as indicated in Figure 4, andtionsystem,the possibilityof eliminatingpurchasedheating
this will be further discussed later on in the guide.

2.4.

SAVINGS POTENTIAL IN ICE ARENAS

Savings potential is understandably of high interest to an ice rink owner since it also can lead to increased economic
performance of the facility. Below, aspects of energy and cost savings potential are discussed to give an ice arena
owner the proper decision-making tools to make the facility more sustainable.

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IIHF GUIDE TO SUSTAINABLE ICE ARENAS 2022

FIELD OF ACTION
2.4 Savings potential in ice arenas
SAVINGS
POTENTIAL

IIHF Guide to sustainable ice arenas 15
2022

Savings potential is understandably of high interest to an ice rink owner since it also can lead to increased
economic performance of the facility. Below, aspects of energy and cost savings potential are discussed togive an ice arena owner the proper decision-making tools to make the facility more sustainable.
2.4.1

2.4.1

Energy savings potential

Energy savings potential

When looking into the energy savings potential of an existing ice rink, the options can often be divided into
When looking into the energy savings potential of an existing ice rink, the options can often be divided into two
two groups of measures: Quick fixes and Long-term solutions. In the table below these two groups aregroups of measures: Quick fixes and Long-term solutions. In the table below these two groups are compared,
compared, but generally it can be said that quick fixes are easy to implement with low/no investment costs,
but generally it can be said that quick fixes are easy to implement with low/no investment costs, while long-term
while long-term solutions require more effort yet yield the biggest savings (most often also with increased
solutions require more effort yet yield the biggest savings (most often also with increased comfort).
comfort).
Table 1.

1. Energysavingsofinmeasure
an ice rink
– Comparison of measure groups.
Energy savings in anTable
ice rink– Comparisongroups.

Definition
Pros

Cons

Quick fixes
Measures that are aimed at single system
adjustments. Require low effort andlow/no investment.
Low/no investment.
Short implementation time.
Immediate savings effect.

Long-term solutions
Measures that require a comprehensive andoften cross-system approach. Require higher
effort and investment.
Minimal operational costs in the long-term.
Optimum functions: e.g. comfortable andhealthy indoor environment.
All-encompassing energy system solution.
Best possible economic performance longterm.
Potentially sacrificed comfort, with Requires larger investments.
unsatisfied visitors as result.
Longer design and implementation time.
Potential risk of function: e.g. mold growthin structures, condensation and othermoisture problems.
Major function and resource inefficiencies
may still remain, e.g. non-sustainablerefrigerants.

Giventhethetwotwomeasuregroupsabove,
it is understandable
that manyarena
may prefer
Given thethecomparison
comparisonofof
measuregroupsabove,
it is understandable
that icemany
iceowners
arena owners
togoprefer
for thetolower-hanging
fruit and onlyfruit
apply
It issavings.
always highly
recommendable
for any ice rinkmay
go for the lower-hanging
andquickonly savings.
apply quick
It is always
highly recommendable
owner
look
for potential
savings,
sincequick
they savings,
may havesinceminimum/noon function andyet improvefor anyfirst
ice torink
owner
first to quick
look forpotential
they mayimpact
have minimum/no
impacton
performancevery
quickly.
Furthermore,
quick
fixes
are
a
good
way
to
engagefacility
ownersintheprocessoffunction and yet improve performance very quickly. Furthermore, quick fixes are a good way to engagemaking
theowners
facility moresustainable,
long-termsolutions
are sustainable,
recommendedwhere
to be applied.
facilityin theprocess ofwheremakingthe facility
more
long-term solutions arerecommended to be applied.
Figure 5 compares the energy performance of a large number of Nordic ice rinks, from which data have beengathered.
The shown
Figure 5 reflect
the averagepurchasedenergya dayof iceFigure 5 compares
thevalues
energyinperformanceof a large
number amountof Nordicoficerinks, fromwhichduring
data have
been
arena
activity.
On the values
left sideinofFigure
the figure,largerareamountrepresented,
and thisenergy
is understandable
gathered.
The shown
5 reflect
thearenas
averageof purchased
during a daysinceof icetheyarebiggerand morewith many
additional
functions that
requirepurchased energy.
They
arena
activity.
On thecomplex
left sidefacilitiesof the figure,largerotherarenasare represented,
and thisis understandable
since
are
somewhatmoredifficultfacilities
to compare.
the additional
rest of the functions
ice arenasthat
are requireby incredible
majority
theytherefore
are bigger
and morecomplexwith However,many otherpurchasedenergy.
somewhatmore
to compare.
rest of the ice arenas are byofsimilarThey
size areandtherefore
capacity, making
themmoredifficultcomparable
in termsHowever,of energythe
performance.
incredible majority of similar size and capacity, making them more comparable in terms of energy
performance.
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FIELD OF ACTIONSAVINGS POTENTIAL

Typical sized ice arenas with conventional technologies purchase more than 3000 kWh of energy (electricity and anyother potential heat sources) per day during the ice season on average. With quick fixes an ice rink owner can reachbelow this limit and improve energy performance with minor savings. The big savings are however only attainable
by applying long-term sustainable solutions, where proven results have shown that existing ice rinks can reachbelow 1500 kWh/day, indicating that energy costs get cut by more than 50%, which in turn make the investments
more profitable than continuing with existing solutions.

Figure 5.

Comparison of energy performance in Nordic ice rinks. The shown values reflect the average amount of purchased energy(electricity and any other potential heat source) during a day of ice arena activity.

2.4.2

Cost savings potential

As discussed above, energy savings measures can be divided into so called “quick fixes” and “long-term solutions”,
where the latter generally yield the best results both in terms of energy and economic performance. However,a typical challenge for an ice rink owner relates to the investments required for the long-term solutions, since they
may become of a significant size. This is the most common reason why only quick fixes are applied first, since theyrequire low/no investment.

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FIELD OF ACTIONSAVINGS POTENTIAL

Figure 6 shows an example where the economic performance of an existing ice rink, that has already applied quick
fixes, is compared with two other “future scenarios”, where the same ice rink is equipped with modern sustainable
solution alternatives 1 or 2. The comparison includes investment (CAPEX) for the alternative solutions as well as all
operating costs (OPEX), including energy and service, for each scenario over a reasonable length of time (often 20
years). This approach to compare economic performance is called life-cycle cost analysis, where all relevant costs
over the long-term are recalculated to a single lump sum by which the economic performance of each scenario canbe compared.
IIHF Guide to sustainable ice arenas

As can be seen in Figure 6, the sustainable long-term solutions show a considerably better2022 economic performance
than continuing with the existing system solution where only quick fixes have been applied. This also means that for
As can be seen in Figure 6, the sustainable long-term solutions show a considerably better economiceach
day that
goesby, the withice rink
owner system
is losingmoney
by continuing
withhavethe existing
system instead of investing
performancethancontinuing
the existing
solutionwhere
only quick fixes
been applied.
insustainablelong-termsolution.
Thisa alsomeans thatfor each daythat goes by, the ice rink owner is losing money by continuing with theexisting system instead of investing in a sustainable long-term solution.

The actual savings potential will vary depending on several factors such as system, size of ice arena, energy prices,
The actual savings potential will vary depending on several factors such as system, size of ice arena, energy
etc., but the main thing to remember is that economic performance of system solutions should always be compared
prices, etc., but the main thing to remember is that economic performance of system solutions shouldonthe belong-term
will showsincewhich
solutionsaves
most saves
money
formoney
the iceforrink
alwayscomparedsinceon theitlong-term
it willshow which
solutionmost
the owner.
ice rink It should also be noted
that
theIt operatingof thescenarios”
areinbasedon actualowner.
should alsocosts
be noted
that“future
the operating
costs inof thethe Figure“future below
scenarios”
the Figure
belowdata
are from existing ice rinks
basedon
actualdata
fromexisting
ice
rinks
that
have
switchedtosustainable
solutions,thevaluesarethat have switched to sustainable solutions, the values are therefore based on reality.
therefore based on reality.

Life-Cycle-Costs, 20-years period
Example from a real project

EUR

Investment

1.800.000

Energy1.600.000

Yearly service costs

Periodic service costs>480’000 EUR
savings in 20 years

1.400.000
1.200.000
OPEX

1.000.000

OPEX

800.000
600.000
400.000

CAPEX

200.000
0

Existing system

Alternative 1

Alternative 2

Figure 6.
6. Life-cycle
cost results
for sustainableenergy solutions(alternative& 2) in an ice 1rink
to existing
system. The
FigureLife-cycle
cost results
for sustainableenergysolutions1 (alternative& compared2) in an ice
rink compared
to existing system.
results show that investing in long-term solutions will yield the biggest savings for the ice rink owner.

The results show that investing in long-term solutions will yield the biggest savings for the ice rink owner.

2.5 Environmental impact of technical solutions
These days, the economy often plays the decisive role in the selection of technical solutions. Nevertheless,other factors such as safety and, not the least, environmental impact are gaining more ground.

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The importance of minimizing energy and water usage as well as the importance of applying sustainableIIHF GUIDE TO SUSTAINABLE ICE ARENAS 2022

18

FIELD OF ACTIONENVIRONMENTAL IMPACT

2.5.

ENVIRONMENTAL IMPACT OF TECHNICAL SOLUTIONS

These days, the economy often plays the decisive role in the selection of technical solutions. Nevertheless,other factors such as safety and, not the least, environmental impact are gaining more ground.
The importance of minimizing energy and water usage as well as the importance of applying sustainable building
materials are themes that are becoming increasingly known to the wide audience, since they are applicable to moreor less any kind building, be it residential, commercial, industrial, etc.
In the world of refrigeration systems and heat pumps, to which ice rinks also belong, the environmental impact of
the refrigerant used in the refrigeration system will also play a significant role whether the facility is sustainable ornot. This is further discussed below.

2.5.1

Refrigerant environmental impact

As more and more facts about climate change have been brought to light, environmental factors have become
increasingly included in the legislation processes around the world, affecting the technology development, including
refrigeration technology. Typical refrigerants that have been used over the years have certainly had an impact on
climate change, causing both ozone depletion and global warming.
Signed in 1987, the Montreal Protocol reduced and then banned chlorine- and bromine- based chemicals as
refrigerants. It was motivated by scientific observations from laboratories, the ground, aircraft, and satellites, which
all indicated that ozone depletion was taking place. Figure 7 compares the ozone layer between the years 1979
and 2011 with the south pole in the center. The deterioration of the ozone layer results in a more intense ultraviolet
radiation from the sun penetrating until the surface of the planet, increasing the risk of sunburns, skin cancer andeye damage.

Figure 7.

The Antarctic ozone hole on September 16 in the years 1979 and 2011 (NASA Earth Observatory, 2012).

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19

FIELD OF ACTIONENVIRONMENTAL IMPACT

Another aspect of climate change, which today is a more pressing topic, is the so-called global warming, which isdefined as an unusually rapid increase in Earth’s average surface temperature over the past century – 0.6 to 0.9
degrees Celsius between 1906 and 2005. Moreover, the temperatures are without a doubt going up further. The main
factor contributing to it are the greenhouse gas emissions released due to human activities.
The main legislation related to global warming in the refrigeration industry is the “F-gas regulation” made in the EUthat aims to control the emissions from fluorinated greenhouse gases (F-gases). One of the measures is phasingout the F-gases by limiting the sales. Every region of the world has its own pace, with EU in the forefront, where thegoal in 2030 is to have one fifth of the sales of 2014.
To understand how refrigerant properties, including environmental impact, have affected the industry over the last
decades, Figure 8 is illustrated. Here refrigerants have been divided into four generations. Up until 1990’s the focus
was on safety and durability, after which the 3rd generation refrigerants were substances with no ozone depletion
potential. The latest generation represents even further environmental advancements that have been implemented,
tackling the global warming effect of the refrigerants.

Figure 8.

History and future of refrigerants divided in 4 generations (Makhnatch, 2018).

Refrigerant properties will be discussed further in this guide when presenting sustainable refrigeration systems.

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20

PROCESSES
CONSULTING AN EXPERT3

BUILDING AND RETROFITTING ICE RINKS –SUSTAINABLE WORKING PROCESSES

This chapter will go through how an ice rink owner can ensure, or at least maximize the probability, that an ice rinkproject becomes successful by consulting an impartial industry expert. A successful project indicates achieving
optimum quality for the lowest possible price as well as on time.
While there are new ice rinks being built still today, most ice rink related projects are retrofits. The retrofitting
process of an ice rink, and how it can be done sustainably, is therefore also discussed further.

3.1.

CONSULTING AN IMPARTIAL INDUSTRY EXPERTWhen an ice rink owner is presented with a situation, where something needs to be investigated, designed, built,
fixed, etc., a natural step (and in many ways also a decisive step for the final outcome of the project) is how the
procurement process is handled.
In the procurement process, regardless if it is public or private, a typical challenge for facility owners is how
to compare different tenders. The most common path is to select the tender with the lowest price, but in many
unsuccessful procurement processes, the presented offers vary enormously in terms of quality. As a result, the client
often ends up choosing the supplier with the lowest price but not the solution with the desired or optimum quality.
This in turn, has a negative impact also on the long-term economy of the client.
Especially in private procurements where offers vary in quality, clients may also select the solution based on best
perceived quality. But the perceived quality may not reflect reality, resulting in that the client ends up paying evenmore for something that still does not fulfill the demands optimally.
The best way to avoid these typical problems in procurement is to clearly specify what kind of system solution is tobe implemented, since it will make the tenders comparable in terms of quality and therefore making the price thedecisive factor. The challenge here, however, is that most facility owners, contractors, and even consultants do notknow which system solution best covers the demands in terms of both quality and (long-term) economy. And even
if they would know, they even more likely lack the knowledge on how the contract documents should be specified
so that the desired system solution also will become reality in the most time- and cost-efficient manner, if at all.

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PROCESSES
CONSULTING AN EXPERT

Figure 9.

The procurement process contains many pitfalls, which mainly occur due to the lack of knowledge, and may lead to low quality

results and/or significant waste of money.

A good way to ensure that the procurement process becomes successful, regardless if it is public or private, is toinclude an unbiased industry expert that can support the client with necessary information so that the quality related
requirements for the project become clearly specified in contract documents. This will result in comparable tenders
in terms of quality in their technical solutions and ensure that the client will be procuring the best solution to coverdemands for the best price. In the ice rink industry this means that the client then will get the most energy andcost-efficient ice rink for the lowest investment cost.

Figure 10. An impartial industry expert can support the ice rink owner in investigating, designing, and specifying the optimum systemsolution in procurement documents. Tenders will as result be comparable in terms of quality, and the client will get the best
possible solution to cover demands for the lowest price.

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PROCESSESRETROFITS

Consulting an impartial expert in ice rink technology is therefore of high importance to achieve a sustainable
ice arena. While there are many consultants out there, an impartial expert is focused on making sure that solutions
created for the client combine excellent performance with good economy and minimal environmental effect, allbacked by latest peer-reviewed scientific research. The work of an impartial expert often consists of developing
energy concepts for newly built or renovated ice rinks to optimize the facility and/or lower its operating costs. Thismeans that the solutions in each project where an impartial industry expert is involved in will maximize the benefitsof the client, and make sure that suppliers continuously update their service in order to fulfill the requirements ofstate-of-the-art technology backed by scientific based data.

3.2.

RETROFITS

As indicated in this chapter, a key component in successful procurement is knowledge. The client is typically not
so well-informed regarding what exactly should be procured, how its requirements should be specified, and why
the chosen quality is the best solution. The best way to tackle this problem is to have an impartial industry expert
guide the client in the right direction. In the ice rink industry this typically this means that the expert will collectinformation regarding the circumstances of the particular project and the client’s needs, in existing facilities oftenby establishing technical status and performing energy audits. Suggestions for system solutions that fit the scopeof the project and fulfill the demands of the client will then be presented.
When the client and the impartial industry expert have decided on the final solution that is to be implemented, theexpert will create the specifications and drawings that are to be used in the procurement process. The specifications
will be precise enough to make sure that received tenders will be comparable in terms of solution quality, while atthe same time respect the principles that are used in public procurement (in case the procurement is done publicly).
This way the client will get the desired system solution for the best price, which in the ice rink industry means themost energy and cost-efficient ice rink for the lowest investment cost.
Furthermore, the industry expert can support the client in auditing and follow up on the project, where it can beensured that the delivered system solution fulfils the requirements and that it also works as intended when put into
operation.

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IIHF Guide to sustainable ice arenas 23
2022

IIHF GUIDE TO SUSTAINABLE ICE ARENAS 2022

PROCESSES
Furthermore, the industry expert can support the client in auditing and follow up on the project, where it
can be ensured that the delivered system solution fulfils the requirements and that it also works as intended
RETROFITS
when put into operation.

Ice rink expert role and actions in energy efficiency development phases

IV - Operation

Follow-up
Supervision of installed system.
Energy optimization.
Improved controls.

III - Implementation

Customer support during
implementation
Competent expert of the customer.
Direct contact with suppliers.

II - Procurement

I - Pre-design

DesignTechnical documentation for procurement.
Bid inspection.
Life-cycle-cost and quality.

Investigation
Measurements on-site.
Energy and refrigeration system analysis.
Localization of errors.

0 - Intro

Technology and energy inventory
Visit onsite.
Complete inventory.
Recommended measures with cost estimations.

In the illustration above, the work process of developing energy concepts is shown for newly built or to berenovated
ice rinks,
in theorder
toprocess
optimize
the facilityenergy
or lowerits operating
Different
haveIn
the illustration
above,
workof developing
concepts
is showncosts.
for newly
built orarenas
to be renovateddifferent
requirements;
therefore,
every
ice
arena
needs
a
tailoredsolution.
ice rinks, in order to optimize the facility or lower its operating costs. Different arenas have different requirements;
therefore, every ice arena needs a tailored solution.

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IIHF GUIDE TO SUSTAINABLE ICE ARENAS 2022

24

ENVELOPE
ROOF AND WALL

4

SUSTAINABLE BUILDING ENVELOPE

The main function of the building envelope is to separate the indoor climate from the alternating outdoor weather
in a controlled manner. Support systems such as heating, ventilation and dehumidification should not have to work
more than necessary in order to maintain the desired indoor climate.

Figure 11. Ice arena with wooden material elements in the building envelope.

The building envelope should therefore be designed and built to handle the local outdoor climate conditionsin the best way possible.

4.1.

ENVELOPE – ROOF AND WALL CONSTRUCTIONS

It goes without a discussion that the main property of the building envelope is its structural durability. However, thepurpose is to separate the indoor environment from the ambient conditions, with the least energy required for themechanical equipment. This implies that heat and moisture transport should be controlled in a proper manner for
the intended application in the prevailing climate conditions.

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25

ENVELOPE
ROOF AND WALL

4.1.1

Insulation

To reduce the capacity required of the heating as well cooling equipment, insulation is used. It is a thermal barrierin the building envelope structure with the aim to halt the undesirable heat transfer consequences, ensuring thatreasonable thermal comfort conditions are achieved at any time of the year.
Materials that can be used for the insulation must have sufficient resistance for the given conditions, which is thegoverning parameter. Since the availability and price of the material depends on the location, there is a wide rangeof wall structure combinations. In Nordic ice rinks, for example, two commonly used materials are mineral wool andpolyurethane.

4.1.2

Air barrier

Minimization of air leakages is required in order to avoid excessive infiltration or exfiltration rates. In ice rinks,
infiltration rate is especially critical for the dehumidification load during the warm part of the season due to thefact that air carries water vapor with it. The heating or cooling demand is also important, since the volume of airthat is transferred in our out by air leakage, impacts the heating or cooling demand. In this section attention is paid
to moisture rather than heat transfer.

Figure 12. Stack effect in an ice rink depending on a time of a year (Rakennustieto, 2007)

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26

ENVELOPE
ROOF AND WALL

Air leaks through openings or space between joints, or cracks in the building structure, thus a continuous air barrier
which seals the whole building envelope is very important. The air barrier material of the wall must seal to the air
barrier material of the roof. Usually, in case of unproperly sealed envelopes, moisture tends to deposit at a discrete
location near the leakage point on the inside of the ice rink arena room.
In Figure 13 an example is shown from an ice rink where evidence of air leakage can be seen. In summertime
the total air pressure difference between indoor and outdoor air is negative at the top of the building - above theneutral pressure line, as shown in Figure 12. And provided there are unintentionally created channels for air toflow, infiltration occurs. Condensation eventually happens since the humid outdoor air meets with a material having
a temperature that is lower than the dew point of the incoming air.

Figure 13. Air leakage traces near the joint between roof and wall.

There are materials available with practically zero air leakage, but it is important to account for the complete air
barrier system - including joints and all the imperfections, since there are forces applied to the air barrier due to the stackeffect, mechanical-system-induced and wind pressures. Therefore, when integrating an air barrier into the wall
structure a proper consolidation method must be applied, since if an air pressure difference cannot move air, it will act
to displace the materials that prevent the air from flowing.

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27

ENVELOPE
ROOF AND WALL

Figure 14. Polyethylene self adhering air barrier (Delta Vent, 2019)

In summary, regardless of which materials chosen, the air barrier must be impermeable to air, able to support thepeak pressure load, continuously applied from foundation to roof, and durable.

4.1.3

Vapor barrier

The nature of diffusion is different than that of air leakage, since it is a much slower process, as a result it is not
a noteworthy indoor air moisture source in ice rinks. The impact on the structure itself, on the other hand, canbe very destructive. The main reason being condensation of the vapor, which appears if the vapor pressure at any
point is lower than its saturation pressure. But the moisture diffusion process itself may not affect the structure,
as long as the moisture is naturally ventilated.
Vapor resistance should be as low as possible in an air barrier in ice rinks, and commonly used materials arecompared in Table 2. The Sd value represents vapor diffusion resistance for a given material and its thickness. It canbe understood that a metal sheet and/or a polyethylene foil are practically completely blocking the vapor diffusion.
Plywood and softwood are also considerable water vapor barriers, and therefore care must be taken when using
these in a building envelope structure. Important to notice that commercially available polyurethane air barriers may
have a very low vapor resistance, implying that there is no risk of condensation due to its location in a wall.

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ance should be as low as possible in an air barrier in ice rinks, and commonly used materials are
IIHF SdGUIDE
TO represents
SUSTAINABLEvapor
ICE ARENAS
2022resistance for a given material and its thickness.
28
n Table 2. The
value
diffusionnderstood that a metal sheet and/or a polyethylene foil are practically completely blocking the
ENVELOPE
ion. Plywood and softwood are also considerable water vapor barriers, and therefore care must
CLIMATE ZONES
hen using these in a building envelope structure. Important to notice that commercially available
ne air barriers may have a very low vapor resistance, implying that there is no risk of condensation
cation in a wall.
Table 2.

Table
2 Vaporforresistancecommonwall structure materials
Vapor resistancecommon wallfor
structurematerial

Material
Metal sheet
Ployethylene foil
Plywood
Softwood
Mineral wool
Plasterboard
Polyurethane air barrier

Thickness (mm)
0.4
0.2
18
28
200
13
0.2

Sd value (m)
1500
70
12.6
5.6
0.26
0.11
0.025

vapor barrieris therefore
generally
as aseenpotential
risk risk
factorlowbenefits,
benefits,
it is
The useof vapor barrieris thereforeseen
generally
as a potential
factorwith
with low
and it andis insteadthat an airwith
barrierlow
withvapor
low vaporresistance shouldbe placedin the iceroof structure.
gested thatsuggested
an air barrier
resistanceshouldbe placedin rink
thewalliceorrinkwall or roof

4.2.

CLIMATE ZONES

Due to the special indoor climate in the arena room of the ice rink, it is preferable to separate it from the outdoor

mate zones
climate with airlocks to minimize unwanted leakage of air, with associated loads such as moist air into the ice rink.

Furthermore, it is recommended that the arena room is well insulated from the other (heated) climate zones in thespecial indoor
climate in the arena room of the ice rink, it is preferable to separate it from thefacility to minimize air leakage, waste of energy and to increase the comfort.
mate with airlocks to minimize unwanted leakage of air, with associated loads such as moist air
The same problem, i.e. air leakage, is often found at the ice resurfacer garage in connection to the ambient. Here it
rink. Furthermore,
it is recommended that the arena room is well insulated from the otherwould be good if an automatic/remote-controlled closing function was applied to minimize air leakage into the arena
mate zonesroom
in theto minimize
air leakage, waste of energy and to increase the comfort.
whenfacility
driving in/out
to dump snow.

roblem, i.e. air leakage, is often found at the ice resurfacer garage in connection to the ambient.
d be good if an automatic/remote-controlled closing function was applied to minimize air leakage
na room when driving in/out to dump snow.

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29

ENVELOPE
CLIMATE ZONES

Figure 15. Open doors either directly towards outdoors, or between comfort and arena zone cause significant energy andmoisture influx into the arena room. In addition, basic uninsulated wooden doors are found between climate zones
in some ice rinks which is not an optimal solution.

In general, it can be recommended to place signs at the doors to the arena room reminding users to ensure that thearena room is kept "closed". Door type should be selected such that is hermetically sealed and with materials thathave a high thermal resistance.

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30

RINK FLOORSSTRUCTURE

Figure 15. Open doors either directly towards outdoors, or between comfort and arena zone cause significant energy and moisture
influx into the arena room. In addition, basic uninsulated wooden doors are found between climate zones in some ice rinks which is
not an optimal solution.

In general, it can be recommended to place signs at the doors to the arena room reminding users to ensurethat the arena room is kept "closed". Door type should be selected such that is hermetically sealed and withmaterials that have a high thermal resistance.

Figure16.16.Doors
betweenandheatedheatedspaces
spacesmust
withthermalresistance, hermetically sealed and normally
FigureDoorsbetweenthe
the coldcold space
space and
must
be be
with
highhigh
thermalresistance,
kept close.
hermetically sealed and normally kept close.

AsAsbringing
informationregarding
regardingclosing
ice haveusersprovenhave toprovento bebringing this
this essential
essential information
closing
doorsdoors
etc. toetc.
all toice allusers
be challenchallenging,an automatic
self-closing
is a recommendedfeature. an
Sometimes
an alternate
functionging, an automatic
self-closing
functionfunction
is a recommendedfeature. Sometimes
alternate functionthat monitors
thatthe andopeningtimeanandproducesan alarm(soundvisual) may
be anasinteresting
solution
themonitors
opening time
producesalarm(sound and/or
visual)may and/or
be an interesting
solutionwell.
as well.

5

SUSTAINABLE RINK FLOORS27

The rink floor is a very important component in the ice rink since it is the base for the ice and the largest heatexchanger in the facility. From a construction point of view, it needs to be in level and from a material perspective
it must withstand the stress from low temperatures and high weight loads. In Europe most ice rinks have themeasure 60×30 m whereas in North America the typical measure is 61×26 m.

5.1.

STRUCTURE

An ice rink floor typically consists of a number of layers illustrated in Figure 17, where the top one is the ice sheetwith a recommended thickness of 25-30 mm. The floor itself is often made out of concrete (designed for freezing
temperatures) for best durability, although sand/gravel and asphalt may used as well due to lower investment costs.
In the top part of the concrete the cooling pipes are typically embedded which provides the heat transfer function
as the load on the ice needs to be transferred to the refrigeration system. The pipes should be placed as close as
possible to the ice sheet (max appr. 35-40 mm between top of pipe and concrete surface) to minimize the resistancein heat transfer, since it otherwise implies that the refrigeration system will be forced to work at a lower temperature(and thus become less efficient).
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RINK FLOORSSTRUCTURE

Under the concrete layer, which is normally about 150 mm thick in total, there is an insulation layer. The insulationis there to reduce the heat load from the ground and the material is normally extruded polystyrene (XPS). Thereis a similar product referred to as EPS which is slightly more permeable to air and moisture, and this must not
be used since it is less resistant to water vapour than the XPS quality.
Below the insulation layer there is very important function – the so-called freeze protection or sub floor heating –which consists of heating pipes. Although there is an insulation layer above, with time, the ground will be cooled
down to freezing temperatures which may result in frost heaving. If that occurs there is a risk of damaging the rinkfloor construction including pipe leakages and associated problems.

Figure 17 Typical layout of and ice rink floor (ASHRAE Refrigeration, 2014)

Vapor retarders are often also recommended to be installed, at least below the concrete layer, to halt moisturetransfer from the ground into the concrete. The material used below the rink floor should not have properties
to support capillary transfer of moisture from the ground towards the rink floor. In case it does, there is a riskthat moisture over time may reach the rink floor structure from the ground and cause damage to the structure.

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32

RINK FLOORSRINK PIPES
IIHF Guide to sustainable ice arenas
2022
Table 3 lists the typical dimensions for rink floor layers and rink piping.
Table 3 lists the typical dimensions for rink floor layers and rink piping.
Table 3.
3. Typical
iceicerinkrinkfloor
andpipe/tube
Table
Typicalfloor
andpipe/tubedimensioning
dimensioning

Parameter
Ice Thickness
Concrete thickness
Insulation thickness
Rink pipe headers diameter
Rink pipe distribution pipes diameter
Rink pipe distribution spacing
Rink floor pipe top – bottom ice distance

5.2.

Size
25-30 mm
150 mm
100 mm
150-200 mm
25-32 mm (plastic), 12.7 mm (copper)
75-125 mm (100 mm typically)
35-40 mm (the less, the better)

RINK PIPES

5.2 are
Rink
pipes
There
mainlythree types of materials used for the rink piping in the ice rink floor through which the secondaryrefrigerant
flows:threeplastic,
steelcopper.used
Plastic
conventional
solutionusedwiththroughmost aqueous
based
There
are mainly
types
of andmaterials
for isthetherink
piping in theice rink
floor
which thesecondaryIn refrigeration
systems
where CO2
is usedas secondaryrefrigerant,
pipesmostcannotsecondary refrigerants.
refrigerant flows:
plastic, steel
and copper.
Plastic
is theconventional
solution plastic
used withbeused dueto thehigh working
pressureInof refrigeration
CO2 which during
normaloperation
typicallyin the rangeof 25 to 30
aqueousbased
secondaryrefrigerants.
systems
where
CO2 is isused
as secondaryrefrigerant,
bar.
Steel
and cannot
copper pipes
can due
handleworkingpressures
andofhavethan plastic,
plastic
pipes
be usedto higher
the highworkingpressure
CO2higher
whichthermal
during conductivity
normal operationisresultinga moreefficientandandbetterenergyperformance.
typically in therange
of 25 heatto 30transferbar. Steelcopperpipes
can handle higher working pressures and havehigher thermal conductivity than plastic, resulting in a more efficient heat transfer and better energy
Material costs vary when comparing copper tubes to steel pipes, but the installation cost of copper tubes isperformance.
often lower since they can be bought at long lengths and rolled out on site. Steel pipes on the other hand are oftendeliveredat fixed
lengths
will havecopper
to be welded
together.
Material costs
vary
whenandcomparingtubes tosteel pipes, but the installation cost of copper tubes isoften lower since they can be bought at long lengths and rolled out on site. Steel pipes on the other hand areoften delivered at fixed lengths and will have to be welded together.

Figure 18. Typical piping layout in Europe with headers on the one short end side.

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RINK FLOORSSUBFLOOR HEATING

IIHF
Guide
sustainable
The piping layout is normally arranged like indicated above
where
thetofeed(supply) ice
andarenas
return headers are placed
2022where the secondaryon the short end side of the ice rink. In the rink floor there is normally a two-pass arrangement
refrigerant is passed to end of the floor and then returned. To allow for effective capacity control of the distribution
secondary refrigerant is passed to end of the floor and then returned. To allow for effective capacity
pumps it is favourable to arrange a so-called reversed return arrangement on the header side. This is also often
ntrol of the distribution pumps it is favourable to arrange a so-called reversed return arrangement on thereferred to as a Tichelmann connection.
ader side. This is also often referred to as a Tichelmann connection.

Figure 19 Two Figure
different
arrangements:
conventional (left)
and reversed
return(right),return
where
the latter
generally
19.headerTwo different
header arrangements:
conventional(left) andreversed(right),whereisthe
latter is generally recommended.
recommended.

e advantage ofThetheadvantage
reversed of
returnis that since
it isis“hydraulicallyit willbalanced”
provide anflow an even flow disthe reversed
returnthat since it isbalanced”“hydraulicallyit evenwill provide
tribution regardlessthe fluid offlow.
headerdesigns
restrictions
to control
the distribution,
tributionofregardlessthe Some
fluid flow.
Someheaderusedesigns
use restrictions
to control
the distribution, which increaich increases ses
the thepressuredrop
andandit cannot
be becapacity
controlled
withinpressuredrop
it cannot
capacity
controlled
withina large
a largeflow
flowrange.
range.

tribution of secondaryrefrigerant
is further
discussedin therefrigeration
chapterof thischapter
guide. of this guide.
Distributionof secondaryrefrigerant
is further
discussedin thesystem
refrigeration
system3 Subfloor
heating/ Freeze protection
5.3.
SUBFLOORHEATING / FREEZE PROTECTION

pipes
are ofnormallyof plastic,
andoftenqualityof the assame
the usedplastic pipes used for thebfloor heating“Subfloor
pipes areheating
normally
madeplastic,madeand oftenof thesame
the quality
plastic aspipes
the secondaryrefrigerant
distribution(see above)with witha pipespacingof approximately
500500mm.
It Itisis important that thesecondaryrefrigerant
distribution(see above)a pipespacingof approximately
mm.
portant that the
subfloor
heating
fulfils
its function
lowestpossibletemperatureso thatit does
subfloor
heating
fulfils
its function
withwith
lowestpossibletemperaturelevel,level,
so thatit does
not unnecessarily cause
unnecessarily
cause
heat
the icesheet itself.
heat
loads
on loads
the iceonsheet
itself.

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34

RINK FLOORSDASHER BOARDS

Figure 20. Principle solution on freeze protection distribution below the rink floor.

When a rink floor has a freeze-protection function, the ground temperature should be maintained at around
3°C. This further indicates that the fluid itself needs to be freeze-protected and a recommended solution here
is often an adequate mixture of water with propylene glycol or equivalent with low enough freezing temperature.

5.4.

DASHER BOARDS

Dasher boards are found in most ice arenas and are generally less of a concern from an energy point of view.
Nevertheless, they are important in terms and function and safety, and an impartial industry expert should
be consulted in the design and procurement of services related to dasher boards.

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ENERGY SYSTEMSREFRIGERATION

Figure 21. Dasher boards fulfil important functions, not the least in terms of safety.

Regular maintenance and status checks are also important to ensure that player/visitor safety is upkept.

6

SUSTAINABLE ENERGY SYSTEMS

Whether the specific ice rink facility is going to be profitable to a major extent depend on the awareness of ice rinkmanagement that energy usage is a major expenditure. Sustainable energy systems in an ice rink present an opportunity for a significantly more cost-competitive ice rental rates, making ice hockey more affordable.
This chapter provides a general overview about the key energy systems an ice rink depends on. For each system
the best practices according to evidence from real installations and research are suggested.

6.1.

REFRIGERATION SYSTEM

Refrigeration system is the largest energy user in an ice rink and often presents the most significant saving
potential. Principally the refrigeration system can be divided into two main subsystems – the primary and thesecondary.

TABLE OF CONTENTS

affordable.
This chapter provides a general overview about the key energy systems an ice rink depends on. For each
IIHF GUIDE TO SUSTAINABLE ICE ARENAS 2022
36
system the best practices according to evidence from real installations and research are suggested.

ENERGY SYSTEMS
6.1 Refrigeration system
REFRIGERATION

Refrigeration system is the largest energy user in an ice rink and often presents the most significant saving
potential. Principally the refrigeration system can be divided into two main subsystems – the primary andthe secondary.

Figure 22. The primary system (on the left) involves a primary refrigerant, it cools a fluid in a secondary system

Figure 22. The primary system (on the left) involves a primary refrigerant, it cools a fluid in a secondary system (on the right) that(on the right) that circulates in the rink pipes.
circulates in the rink pipes.

••

•

•

••
••

Primarysystemis thecentralwithrefrigerant,
refrigerant,
typically
placeda technicalPrimarysystemis thecentralrefrigeration
refrigeration plant
plant withtypically
placedin aintechnicalroomroomoror an
outdoorcontainer.
A
distinct
partofa
primarysystemarecompressors,heat
exchangers
among
an outdoor container. A distinct part of a primary system are compressors, heat exchangers among other
other components.
components.
Secondary system is the cooled fluid circulation system that absorbs heat from the ice slab andSecondary system is the cooled fluid circulation system that absorbs heat from the ice slab and transtransports it to the primary refrigeration system where it is cooled. It is comprised of a longports it to piping
the primarysystemwhere
cooled.
is comprisedof apipes
long distribution
distribution
thatrefrigeration
is embeddedin therinkit isfloor
andIt with
commonconnectedpiping
to thethatisembedded
in
the
rink
floor
and
with
commonpipes
connected
totheprimarysystem.
primary system.
Refrigerant
is thefluidthatthatisisusedused inin thethe primary
Refrigerant
is thefluid
primarysystem.
system.
Secondaryfluid
is thefluid
fluidthatthatisisusedused inin thethe secondary
Secondaryfluid
is thesecondarysystem.
system.

6.1.1 System
Systemconfigurations
6.1.1
configurations

Ice rink refrigeration system can principally be divided in two types – direct and indirect.

Ice rink refrigeration system can principally be divided in two types – direct and indirect.
indirectsystemsystemhashasaaseparation
separation between
primary
refrigerant
that thatis usedin theinrefrigeration
cycle, while
AnAn
indirect
betweenthe
theprimary
refrigerant
is usedthe refrigeration
cycle,
the secondary fluid is circulated through the rink piping system and brought to the evaporator.
while the secondary fluid is circulated through the rink piping system and brought to the evaporator.
A direct system has one fluid in the complete system used without separation, i.e., the same refrigerant that
evaporates in the rink pipes is also passed through the compressors.

32

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A more widespread configuration is the indirect configuration, which is partly because of the popularity NH3 has had
as a primary refrigerant. The reason why NH3 systems need indirect design is that a separate rink pipe loop allows
to avoid the use of toxic NH3 to be circulated in the rink pipes, which also reduces the total charge.

Figure 23. Two main refrigeration system configurations in ice rinks, simplified schematic.

The advantage of a direct configuration is the ability to achieve a more even ice temperature, less pump work, andthus a higher energy efficiency compared to the indirect design. The key disadvantage is the capital cost and limited
refrigerant choice.

6.1.2

Primary system

When designing the primary system, several ground principles shall be followed to achieve the best long-term
performance.

6.1.2.1 Selection of refrigerants
Many different fluids (media) can be used as refrigerants; however, for practical reasons the actual usage is limited
to a few candidates. Of great importance are the safety (flammability, toxicity, etc.) as well as the environmental
impact. The latter has in recent years turned the focus in the direction of natural refrigerants. In Table 4, a coupleof candidates are listed. As can be seen, natural substances have a significantly lower Global Warming Potential (GWP), thus natural refrigerants do not have long-lasting detrimental effects on the nature when leaked into
the atmosphere, which is the case for synthetic refrigerants.
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ENERGY SYSTEMSREFRIGERATIONIIHF Guide to sustainable ice arenas
2022
Table 4.

Table 4 GWP and safety classes of several refrigerants.
GWP and safety classes of several refrigerants.

Refrigerant
R744 (carbon dioxide)
R717 (ammonia)
R290 (propane)
R404A
R134a
R513A
R1234yfType
NaturalNaturalNaturalSynthetic
Synthetic
Synthetic
Synthetic

Toxicity
Non-toxic
Toxic
Non-toxic
Non-toxic
Non-toxic
Non-toxic
Non-toxic

Flammability
Non-flammable
Low
High
Non-flammableNon-flammableNon-flammable
Low

GWP
1
0
3
3922
1430
631
4

6.1.2.1.1 Synthetic refrigerants
R22 (HCFC-group)
6.1.2.1.1
Synthetic refrigerants
This refrigerant
is normally only referred to as R22 and is a synthetic compound belonging to the HCFC-group.
R22 (HCFC-group)
Due toits “ozone
eating”
properties
is subjecttotoasphaseout inparts ofthe world.belonging to the HCFC-group.
This
refrigerant
is normally
onlyitreferred
R22 andis mosta synthetic
compoundDue
to its R407C,“ozone eating”
properties it is subject to phase out in most parts of the world.
R134a,R410A,
etc. (HFC-group)

Togetherwith
the R407C,
natural etc.
refrigerant
ammonia, these are the refrigerants found mostly in
R134a,R410A,(HFC-group)
typical/conventional
ice naturalrinks today.
This groupconsistsof different
is normallyreferred
Together with therefrigerant
ammonia,these
are the alternatives
refrigerants andfoundmostly injust
typical/conventional
to as “HFCs”
which
are
synthetic
compounds.
HFCs
have
no
effectontheozone
layer,
and
they
are
still
widelywhich are
ice rinks today. This group consists of different alternatives and is normally just referred to as “HFCs”
accepted.
Due tocompounds.
their greenhouseproperties,
theya “final
also subject
syn-thetic
HFCs haveno effect
on arethe notozone
layer,solution”
and theyand
are arestilltherefore
widely accepted.
Due to theirto phaseout.
green-house properties, they are not a “final solution” and are therefore also subject to phase out.
R1234yf, R1234ze, R513A, etc. (HFO-group)

R1234yf, R1234ze, R513A, etc. (HFO-group)

In orderto mitigate
the greenhouseeffect of
the HFCs,
replacement
chemicals
are proposed– HFOs – HFOs
In orderto mitigate
the greenhouseeffectof theanother
HFCs, anotherreplacement
chemicals
are proposed(hydrofluoroolefins).
These
synthetic
refrigerants
havemediumdo notnotdeplete
depletethe ozone(hydrofluoroolefins).
These
synthetic
refrigerants
havemediumtotovery
verylow
lowGWPGWP values
values andand dothe ozone
However,have reported
about
other environmental
and healthconcerns
layer. layer.
However,
several several
studies studies
have reported
about otherenvironmental
and health concerns
that
HFOs introduce.
that HFOs
introduce.
Whenleakedintotheatmosphere,
in
only
10-14
days
HFOs
form
into
anotherchemicalWhen leaked into the atmosphere, in only 10-14 days HFOs form into another chemical trifluoroacetic acid (TFA).
trifluoroacetic(TFA).
Thecause,main problem
cause, suggested
variousstudies,areontheThe main acidproblemTFAssuggestedTFAs
by various
studies, arebythe
negative
effectsthenegative
immune systemeffectsontheimmunesystemandhumandevelopment,cancerandotherdetrimental
healthcomplications.
and human development, cancer and other detrimental health complications. (Atmosphere, 2022)(Atmosphere, 2022)

6.1.2.1.2 Natural
Naturalrefrigerants
6.1.2.1.2
refrigerants
R290 R290(Propane)(Propane)
Propaneis a naturalcompoundin the HC-groupoften referredas the hydrocarbons.
Onedrawback
major drawback
Propaneis a naturalcompoundin the HC-groupoften referred
to as thetohydrocarbons.
One major
the flammability
andtodue
the safety
aspects,
propanebe only
usedinonly
in an indirect
system,confined inis theisflammability
and due
thetosafety
aspects,
propanecan becan
used
an indirect
system,confinedwell-ventilated technicaltechnical room
placedoutdoors.
Nevertheless,in recentcommercialization
in a awell-ventilated
roomor orplacedoutdoors.
Nevertheless,in years
recenta significant
years a significant
of R290 refrigerationin various
applications
hasapplications
been observed.
commercializationof R290plants
refrigeration
plantsin various
has been observed.

R717 TABLE(Ammonia)
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ENERGY SYSTEMSREFRIGERATION

R717 (Ammonia)
Ammonia is a commonly used refrigerant in ice rinks. It is a natural substance with the chemical formula NH3, which
has been used as refrigerant since “the beginning”. It is environmentally friendly and efficient but also flammableand toxic. The use of ammonia requires well designed safety measures which drives the cost; therefore, ammonia isnormally only used in larger refrigeration plants. For safety reasons ammonia is normally not allowed to use insideclosed spaces with people present such as supermarkets, ice rinks, etc. It can still be used as primary refrigerant(in the machine room) but will require a secondary refrigerant which transports “the cold” from the machine room
to the cooling object (i.e. ice sheet).

R744 (Carbon dioxide)
Carbon dioxide is also natural substance with the chemical formula CO2. It has a long history as a refrigerant andhas recently become a standard solution in ice rinks due to its combination of favourable properties. As primaryrefrigerant CO2 is generally less efficient than ammonia in warm climate, but the non-flammable and non-toxic
properties offers technical advantages which makes it very interesting.
The unique characteristics give R744 an advantage in terms of heat recovery, meaning that especially in ice rinks
where both cooling and heating demands need to be covered, the refrigerant can often be the most energy andcost efficient solution. CO2 is also a safe refrigerant compared to other sustainable alternatives such as propane orammonia, where e.g. with ammonia a small leakage of 0,5 kg can already cause a lethal environment in a typicalrefrigeration machinery room.

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ENERGY SYSTEMSREFRIGERATIONSUMMARY:

Figure 24. The global tendency is to “return to the roots” and select natural refrigerants (Danfoss).

There are many more refrigerant alternatives out there, but this document limits the discussion to these above since
they are relevant to the topic. As a final comment to the primary refrigerants, it can be said that due to the focus
on environmental issues and sustainability, the industry direction is natural refrigerants and/or newly developed
synthetic alternatives. The latter is a hot topic today where intensive research and development takes place.

6.1.2.2 Heat recovery function
In ice rinks, the largest energy savings potential can often be found in optimizing the heat recovery from therefrigeration system, and therefore minimizing the demand for a supplemental heat source. An energy balance in an
ice rink that covers 100% of its heating demand by heat recovery from refrigeration is shown in Figure 25.

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ENERGY SYSTEMSREFRIGERATIONIIHF Guide to sustainable ice arenas
IIHF Guide to sustainable2022
ice arenas
2022
balance in an ice rink that covers 100% of its heating demand by heat recovery from refrigeration is shown
balancein Figure25.in an ice rink that covers 100% of its heating demand by heat recovery from refrigeration is shownin Figure 25.

Figure 25. Energy balance in a Nordic training ice rink with 8-month season.

Figure 25. Energy balance in a Nordic training ice rink with 8-month season.
Figure 26 shows an example
from
Nordicbalance
ice rink
thetraining
coolingin blue,season.
heating demand in red,
Figure25.aEnergy
in awith
Nordicicedemandrink with 8-month
Figure26heatshows
an offexamplefrom a system
Nordicinice
rinkHere
withit cantheclearlycoolingdemandin blue, heating demand in red, andandavailable
comingthe refrigeration
green.
be seenthat considerably
Figure26
showsanexamplefromaNordic
ice
rink
with
the
coolingdemandinblue,heatingdemandin red,savings
in heating
achievable
withrefrigeration
optimized heatsystem
recovery.
graphindicates
available
heatarecomingoff thein Furthermore,
green. Herethe
it canclearlybe thatseenit isthat considerably savings inandinterestingavailable heat
offat
the
systemHere
it canclearlybe heating
seen thatconsiderably
often
to notcoming
only looktherefrigeration
heating demands
of inthegreen.
ice rink
itself,but alsootherdemands
heatingareachievablewith optimized
heat heatrecovery.
Furthermore,thethegraphindicatesthatititisis often interesting tosavings
inheatingareachievablewithoptimized
recovery.
Furthermore,graphindicatesthatin close proximity to the facility that may also be potentially provided with this “free heat”.

notlook attotheof theice rink
itself,butitself,
alsobutotherdemands
in close proximity to theoftenonlyinteresting
notheating
only lookdemands
at the heating
demandsof theice rink
alsoheatingother heating
demands
inclose
proximitytothefacility
that
may
also
be
potentiallyprovided
with
this
“free
heat”.
facility that may also be potentially provided with this “free heat”.

Figure 26. The refrigeration system usually releases more heat than what a typical ice rink needs. It is therefore interesting to lookfor heating demands beyond an ice rink.

Figure26.TheThe
refrigeration
systemusually
releasesmorewhaticea rinktypicaliceIt rinkneeds.interesting to look
Figure 26.
refrigeration
systemusually
releasesmore heat
thanheat
whatthana typical
needs.
is therefore
36
for heating demands
beyond an ice rink.
It is therefore interesting to look for heating demands beyond an ice rink.

36

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42

ENERGY SYSTEMSREFRIGERATION

The heat recovery system can also be optimized by connecting the refrigeration system to a geothermal storage,
which provides further possibilities both during warm and cold weather conditions. When warm, the storage may
be used to improve the (sub-)cooling of the refrigeration process, resulting in a higher energy efficiency of thesystem, as well as storing excess heat in the boreholes. The very same heat can later be used during colder periods
when there is an increased demand for heat in the facility.
An optimized heat recovery system can therefore cover the entire heating demand of an ice rink, even during colder
periods, eliminating the need for any external heat source. In fact, reference systems have proven so efficient, thatthey may be used to export heat to nearby facilities such as swimming pools.

6.1.2.3 Modern primary refrigeration system solutions
The primary refrigeration technology choice has a considerable effect on the function of the facility and resource
efficiency for the whole economic lifespan of the system, typically 15-20 years. Out of a vast majority of options
to select from, the most optimum alternatives are CO2 or NH3 as the primary refrigerants. If local expertise in
those refrigerant technologies is limited, synthetic refrigerant alternatives may be considered, however taking into
account the aspects that are described in chapter 6.1.2.1.

6.1.2.3.1

CO2 as a primary refrigeration system

After the first ice rink system using carbon dioxide, CO2, as secondary refrigerant was built in 1999, it took until
2010 before the first ice rink using CO2 as a primary refrigerant was realized. Today the number of ice rinks in
Europe and North America using CO2 technology is significant.

Figure 27 The first CO2 primary refrigerant system in ice rink in Europe was installed in 2014 in Gimo, Sweden.
Picture source: Google maps.

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ENERGY SYSTEMSREFRIGERATION

CO2 direct & CO2 indirect
Today CO2 systems are becoming a standard solution in ice rinks, however being divided into direct expansion (DX)systems and indirect systems. The main difference is that in the DX system, the CO2 fluid also goes in the distribution pipes (rink floor), while in the CO2 indirect system a different secondary refrigerant is used in the rink floor.
Furthermore, in the CO2 indirect system a heat exchanger (evaporator) is used between the primary and secondaryrefrigerant circuits. For the rink floor distribution in indirect systems, aqua ammonia is today recommended to be
IIHF Guide to sustainable ice arenas
used as secondary refrigerant due to that it requires much lower pumping power than other commonly used alter2022
natives, such as ethylene glycol and calcium chloride.

Both DX and indirect solutions shall be designed with heat recovery before the condenser, and it is the feature
Both DX and indirect solutions shall be designed with heat recovery before the condenser/gas cooler, and it is thethat allows such solutions to outperform the alternatives, especially in ice rinks with high heating demands.
feature that allows such solutions to outperform the alternatives, especially in ice rinks with high heating demands.

Figure28.indirect
Principleof aleft
CO2
indirectandwithCO2heatDX to
the right, with heat recovery.
Figure 28. Principle ofa CO2
to theand
CO2 DXtotothe
theleftright,
recovery.

Both systems
systems have
havetheir
theirpros
prosandandcons
conswhenwhencompared
comparedtotoeachother,
listedin TableBotheachother,
as aslistedin Table
5. 5.
Table 5.

Pros
Cons

Table 5. theGeneraldifferences
between the possible CO2 configurations.
General differences between
possible
CO2 configurations.

CO2 DX
CO2 indirect• More efficient than CO2 indirect, less • Safer due to less charge
compressor work needed• Lower investment• More accurate ice temperature control• More CO2 charge thus theoretically less safe • Less efficient due to; heat exchange in theevaporator, more compressor work needed• Higher investment than indirect
and more pump power• Requires a secondary fluid in the rink floor

TABLE OF CONTENTS
In general, it can be said that direct (DX) solutions normally suits better in new construction or when a rink

IIHF GUIDE TO SUSTAINABLE ICE ARENAS 2022

44

ENERGY SYSTEMSREFRIGERATION

In general, it can be said that direct (DX) solutions normally suits better in new construction or when a rink floor
is replaced, since it requires metal pipes for the distribution. Due to the higher investment and lower energy
consumption a longer ice season is also positive from a profitability point of view.

Guide
to sustainableiceinarenas
Indirect systems offer a slightly lower investment since “normal” IIHF
plastic
pipes
may be used
the rink floor.
2022
On the other hand, this solution is slightly less efficient which increases the operating cost somewhat.

C
A: Compressors

D

B: Heat recovery heatexchanger

B

C: Gas coolerF

D: Subcooler

EAG

E: Ice rink tube system
F: CO2 accumulator
G: Additional evaporator

FigureOverviewsystemof a CO2
refrigeration
system in an ice rink.
Figure 29. Overview of a CO2
DX 29.
refrigerationin DX
an icerink.

At theAtend
day,day,
thethechoiceofoftechnicalbased ononaacombination
combinationof of
facility
relatedthe ofendtheof thechoicetechnicalsolution
solution will
will bebe basedfacility
relatedconstraints,
constraints,
energyprofileandfinancialconsiderations
which
will
impacttheenvironmental
profileaswellenergy profile and financial considerations which will impact the environmental profile as well as the profitability.
as the profitability.

6.1.2.3.2 NH3 as
NH3as a primaryrefrigeration
6.1.2.3.2
a primaryrefrigeration
systemsystem
As describedin chapter
6.1.2.1,
ammonia
is a widelyused refrigerant
ice rinks
theartificial
first artificial ice
As describedin chapter
6.1.2.1,
ammonia(NH3)(NH3)
is a widelyused refrigerantin iceinrinks
since since
the first
rinkswerewereintroduced.
introduced.AA traditional
traditional fully
a moremodernform, theseice rinks
fully indirect
indirect NH3
NH3system
systemisisaaprovenprovensolution.
solution.In In
a moremoderntoday offer
quantities(<50kg),high efficiency,
good capacity
regulation
and a andlong service
form,systems
these systems
todaysmall
offer charge
small charge
quantities(<50kg),high efficiency,
good capacity
regulation
a longlife.
service life.
A factor
thatincreasingly
has increasingly
becomea decisivefor changing
is that ammonia
is a more
A factorthat hasbecomea decisive
reason reason
for changing
systemssystems
is that ammonia
is a moredangerous
refrigerant
for humans.
thoughmodernsolutions
have
succeededin reducing
refrigerant charge
dangerous
refrigerant
for humans.
EvenEven
thoughmodernsolutions
have
succeededin reducing
thetherefrigerant
there
is stilla riskof ofpersonal
injury.
chargeconsiderably,
considerably,
there
is stilla riskpersonal
injury.
is a colorlessgasa witha strong
and irritating
smell.
Itsdanger
main danger
to humans
is its toxicity.
Two minutes of
NH3 isNH3
a colorlessgas withstrongand irritating
smell. Its
mainto humans
is its toxicity.
Two minutes
exposure
1000ppm
ppmofofammonia
ammonia may
may lead
medicalattention,
while
two twominutes
at a concentrationof exposure
to to1000
lead totothe
theneedneedforfor
medicalattention,while
minutes
at aconcentration of 10,000 ppm means that the probability of death is over 5%. However, the advantage of
TABLE
OF CONTENTS
ammonia
is thatmost people can already smell it at 5-10 ppm. Furthermore, there are few who can withstand
100 ppm, which means a warning in good time of any leakage or release. By far the greatest risk zone is theIIHF GUIDE TO SUSTAINABLE ICE ARENAS 2022

45

ENERGY SYSTEMSREFRIGERATION

of 10,000 ppm means that the probability of death is over 5%. However, the advantage of ammonia is that mostpeople can already smell it at 5-10 ppm. Furthermore, there are few who can withstand 100 ppm, which meansa warning in good time of any leakage or release. By far the greatest risk zone is the refrigerating machine room,
where a very small leak, less than 1kg, can create a life-threatening concentration.

Figure 30. A modern fully indirect NH3 refrigeration system.

The disadvantages compared to direct system solutions that can be mentioned, are the slightly higher energy
consumption for the auxiliary equipment (fans and pumps). Furthermore, the heat exchanges on both the cold andwarm side cause losses in the overall system. As emphasized previously, heat recovery has a key role in an ice
rink's operating economy, and for ammonia the inherent properties are less favourable than for CO2, which makes
it difficult to produce the heat at the temperature level that is needed in an ice rink. In general, these systems may
be supplemented with, for example, a heat pump or district heating to cover the needs completely.
In summary, ammonia is a very efficient refrigerant that, from a theoretical perspective, surpasses CO2 in terms ofcooling performance. In practice, due to the factors mentioned earlier, the CO2 technology properly designed becomes safer, cheaper, more efficient and normally lead to a lower life cycle cost.

6.1.3

Secondary refrigeration system

The secondary refrigerant is the heat transfer fluid which brings the heat from the cooling object (rink floor) to theprimary refrigerant via the evaporator in an indirect refrigeration solution. This fluid is sometimes referred to as;
secondary coolant, heat transfer fluid, brine, etc.
The thermophysical properties of these fluids can have a large impact on the overall performance of the refrigeration
system. Secondary refrigerants most typically are aqueous solution, with a concentration adapted to an appropriate
freezing point for the operating conditions of the specific system.
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ENERGY SYSTEMSREFRIGERATION

6.1.3.1 Commonly used secondary refrigerants
The most common secondary refrigerants used in ice rinks are:
•
•
•
•
•

Ethylene glycol (EG)Calcium chloride (CaCl2)
Aqua ammonia (NH4OH)
Carbon dioxide (CO2)
Potassium formate (KF)

and less commonly:•
Propylene glycol (PG)•
alcoholacetate(EA) (KAc)- EthylPotassium•
Potassium acetate (KAc)

IIHF Guide to sustainable ice arenas
2022

These
fluidsmayhavehaveadvantages
advantagesandanddisadvantages
disadvantages forfor use in ice
These
fluidsmay
ice rink
rinkrefrigeration.
refrigeration.Safety
Safetyconsiderations
considerations will
will include
which
to risks
from inhalation,
ingestion,
and/or eye
and whichincludetoxicity, toxicity,which refers
to refers
risks frominhalation,
ingestion, skinand/or skineye exposure,andexposure,flammability,
flammability,which
refers
to
the
flash
point
(also
known
as
auto-ignition
temperature).
Environmental
refers to the flash point (also known as auto-ignition temperature). Environmental considerations include toxicity
includetoxicity and damage to local ecosystems.
andconsiderations
damage to local
ecosystems.

Figure 31. Thermophysical properties of discussed secondary refrigerants at -10°C having freezing points of -20°C (Kilberg, 2020).

Figure 31. Thermophysical properties of discussed secondary refrigerants at -10°C having freezing points of -20°C (Kilberg, 2020).

Low dynamic viscosity, high conductivity, high specific heat, and low density are all advantageous for reducing
pumping power and efficiently transferring heat. It is clear from the figure above that aqua ammonia has
favourable thermophysical properties. On the other hand CO2 is difficult to compare since it is used as a
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47

ENERGY SYSTEMSREFRIGERATION

Low dynamic viscosity, high conductivity, high specific heat, and low density are all advantageous for
IIHF Guide to sustainable ice arenas
reducing pumping power and efficiently transferring heat. It is clear from the figure above that aqua ammonia
2022
has favourable thermophysical properties. On the other hand CO2 is difficult to compare since it is used asa volatile (phase changing) fluid.
Figure32. Summary
aboutadvantages
main advantages
and disadvantages
themost common
secondaryin ice rinks.
Figure 32.
Summary
about mainand disadvantages
with thewithmostcommonsecondaryfluids influids
ice rinks.

Secondary fluid
Brine (Calcium Chloride)

Pros
Non-toxic,
non-flammable,lowviscosity, plastic material for rinkpiping allowed, lower investment.
Carbon dioxide
Non-toxic, non-flammable, very low
viscosity,
high
heat
transfer
properties, low pumping power,
allows more even ice temperatures.
Propylene glycol
Quasi non-corrosive, low fire hazard,
non-toxic, low environmental hazard
risk, plastic material for rink piping
allowed, lower investment.
Ethylene glycol
Plastic material for rink piping
allowed, lower investment.
Potassium Acetate and Low environmental hazard risk,
Potassium Formate
relatively low corrosiveness, lowviscosity, low pumping power, plastic
material for rink piping allowed, lower
investment.
Aqua ammonia
Low viscosity, high heat transfer
properties, low pumping power,plastic material for rink piping
allowed, lower investment.

Cons
High corrosivity, low specific heat,
relatively high pumping power.
High pressures, metal material for rinkpiping required, higher investment.
High viscosity, high pumping power.

Toxic, high environmental hazard risk,
high viscosity, high pumping power.
Toxic.

Toxic, however possesses very low
danger due to low ammonia
concentration.

6.1.3.1 Modern secondary system solutions

6.1.3.1 Modern secondary system solutions
Out of the available fluid options presented above, the optimum alternatives in an ice rink, from a technicalOut of the available fluid options presented above, the optimum alternatives in an ice rink, from a technicalperspective, are CO2 or aqua ammonia, which are here elaborated further.
perspective, are CO2 or aqua ammonia, which are here elaborated further.
6.1.3.1.1 CO2refrigerant
6.1.3.1.1
CO2asassecondary
secondaryrefrigerant

Using carbon
severaladvantages
overover traUsing
carbon dioxide
dioxide as
asthe
thesecondary
secondaryrefrigerant
refrigerantininthe
thedistribution
distributionsystemsystembrings
bringsseveraladvantages
traditional
solutions,calciumchloride
glycol.
The most
prominent
onesthat
areCO2
thatutilizes
CO2 utilizes
the change
ditional
solutions,e.g.e.g.
calciumchlorideand andglycol.
The most
prominent
ones arethe phase
phase changeand(evaporation)
has a which
low viscosity
leads to a lower
considerably
lowerpumping
power. done
(evaporation)
has a low andviscosity
leads towhicha considerably
pumping
power.
Measurements
Measurements done in ice rinks indicate that about 20-25 % of the refrigeration system energy consumption
in ice rinks indicate that about 20-25 % of the refrigeration system energy consumption stems from the auxiliarystems from the auxiliary equipment, such as fans and pumps. By applying CO2 as the secondary refrigerant
equipment, such as fans and pumps.
pumping power can be reduced to about 1 kW compared with traditional fluids which require 5-15 kW. Thus,
the energy consumption of the auxiliary equipment in such a refrigeration system becomes less than 3% of
the grand
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By applying CO2 as the secondary refrigerant pumping power can be reduced to about 1kW comparedwith traditional fluids which require 5-15 kW. Thus, the energy consumption of the auxiliary equipment in sucha refrigeration system becomes less than 3% of the grand total.
CO2 may be used as the secondary fluid only, where it is cooled by another primary refrigeration plant. Another, evenmore efficient solution is a direct system where it serves as both - secondary and primary refrigerant, see Figure
28 in Chapter 6.1.2.3.1.

Figure 33. CO2 receiver in a large ice arena where CO2 is circulated in the rink piping.

The pipes in the ice rink floor must be adapted to the properties of CO2, as the substance has a much higher working
pressure than other secondary refrigerants typically used. Welded steel pipes used to be the norm but are nowadays
often substituted with more convenient copper tubes designed for ice pads. Therefore, in existing ice rinks where
the rink floor has plastic pipes and is in good conditions, CO2 is typically not economically profitable, but rather
aqua ammonia shall be used in the existing piping if the materials are compatible.

6.1.3.1.1

Aqua ammonia as secondary refrigerant

Aqua ammonia is becoming increasingly popular especially when retrofitting existing and building new ice rinks.
The first ice rink installation with ammonia water in Sweden took place in 2007 and in 2018 there were at least
34 installations in indoor ice hockey ice rinks and today this number is considerably higher. Most Nordic ice rinks
use CaCl2 but the trend is clearly going direction CO2 and ammonia-water.

TABLE OF CONTENTS

working pressure than other secondary refrigerants typically used. Welded steel pipes used to be the norm
but are nowadays often substituted with more convenient copper tubes designed for ice pads. Therefore, inexisting ice rinks where the rink floor has plastic pipes and is in good conditions, CO2 is typically not
IIHF GUIDE TO SUSTAINABLE ICE ARENAS 2022
49
economically profitable, but rather aqua ammonia shall be used in the existing piping if the materials arecompatible.

ENERGY SYSTEMS
6.1.3.1.1
Aqua ammonia as secondary refrigerant
REFRIGERATION
Aqua ammonia is becoming increasingly popular especially when retrofitting existing and building new ice

Pump size for fluids: CaCl2

760 mm

940 mmrinks. The first ice rink installation with ammonia water in Sweden took place in 2007 and in 2018 there wereat least 34 installations in indoor ice hockey ice rinks and today this number is considerably higher. Most
Nordic ice rinks use CaCl2 but the trend is clearly going direction CO2 and ammonia-water.

NH4OH

Figure 34. Required pump size difference between CaCl2 pump (on the left) and NH4OH pump (on the right), for the same cooling
Figure 34. Required pump size difference between CaCl2 pump (on the left) and NH4OH pump (on the right),
capacity of 250 kW at -10/-8°C.
for the same cooling capacity of 250 kW at -10/-8°C.

The reason why the number of installations is growing so rapidly, is primarily the good experience from theinstallations.
As mentioned,
with CaCl2 is
hasgrowing
motivatedthe market
to look atthe
alternatives,and ammoniaThe reason why
the numberissuesof installations
so rapidly,is primarily
good experiencefrom thewater does offer practical advantages as well as some disadvantages. A further reason for the interest in
installations. As mentioned, issues with CaCl2 has motivated the market to look at alternatives, and ammonia-wateraqua ammonia is the rapid growth CO2-systems. To use CO2 as primary refrigerant with its high operating
does offer practical advantages as well as some disadvantages. A further reason for the interest in aqua ammonia ispressures in combination with a titanium alloy evaporator, drives the cost of the evaporator andthe rapid growth CO2-systems. To use CO2 as primary refrigerant with its high operating pressures in combinationconsequently of the whole refrigeration unit. If ammonia water is being used, normal stainless steel can bewith a titanium alloy evaporator, drives the cost of the evaporator and consequently of the whole refrigeration unit.
If ammonia water is being used, normal stainless steel can be used in the evaporator, thus saving considerablyon the investment. This cost offsets the secondary refrigerant
retrofit cost which is typically of the same order43
of magnitude. Consequently, the retrofit is “paid” by the cheaper evaporator, and then the system has half
the pump power for the rest of its technical life compared to conventional solutions.
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50
IIHF Guide to sustainable ice arenas

2022
ENERGY SYSTEMSHEATINGused
in the evaporator, thus saving considerably on the investment. This cost offsets the secondaryrefrigerant retrofit cost which is typically of the same order of magnitude. Consequently, the retrofit is “paid”
by the cheaper evaporator, and then the system has half the pump power for the rest of its technical life
compared to conventional solutions.

6.2
systems
6.2. Heating
HEATINGSYSTEMS
6.2.1
in in
iceicerinks
6.2.1 Heat
Heatdemand
demandrinks
Ice rinks
rinkshave
havea anumber
numberofofdifferent
differentheating
heatingrequirements.
requirements.SpaceSpace
heating
is required
to provide
comfortIce
heating
is required
to provide
comfortin inpublic areas
areas andandthethearena
arenaroomroomatata acomfortablecomfortablelevel.
level.Public
Publicareas
areas
such
as locker
rooms
officesrequirepublicsuch
as locker
rooms
andandofficesrequiretemperature ofof aroundaround 20°C while
while thethe arena
arena room
room may
may bebe kept
kept atatessentiallyessentiallyanyanytemperaturetemperature depending
depending on
aa temperature
typetypeof arena,
activityand preferences,
but in mostarenas it ranges
5 to 15°C.
Hot5water
for showers
onof arena,
activityand preferences,
but conventionalin most conventional
arenasfrom
it ranges
fromto 15°C.
Hot
water
showers
the locker
rooms
and resurfacer,needs
be heated toa temperaturein the forlockerroomsin andresurfacer,needs
to be heated
to atotemperatureabout
55-60°C inaboutorder55-60°C
to preventinto preventthe reproduction
theorderreproductionof legionellabacteria.of legionella bacteria.

Figure 35. Ice rinks are heatingFigure
intensive
facilities
withheating
many demands.
35. Icerinks areintensive facilities with many demands.

To summarise - an ice rink uses considerable amounts of heat for its different heat demands such as:
To summarise - an ice rink uses considerable amounts of heat for its different heat demands such as:SpaceSpaceheating
heatingo
Arena
Arena room roomo Surrounding spaces
Surrounding spaces§ Locker rooms		
Locker rooms§ Cafeteria
		Cafeteria§ Etc.
•
Ventilation• Ventilation• Hot tap watero Showerso Resurfacing water
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ENERGY SYSTEMSHEATING•••

Hot tap waterShowers
Resurfacing water
Subfloor heating / Ground freeze protection
Melting pit

It can be mentioned that an ice rink with a tempered arena room, 5-10°C, uses about the same amount ofheat as cooling!

6.2.2

Heat sources in ice rinks

There is a large variety of heating methods and sources being used in ice rinks. As very often mentioned inthis document, heat recovery makes a lot of sense since so much heat is used – and produced!
Typical auxiliary heat sources may be:•
Gas or oil•
District heating•
Electricity
BoilerResistance heaters•
Heat pump
External heat source (air, geothermal, etc.)
Internal (refrigeration system coolant, etc.)•
Wooden pellets
Whereas internally:•
Heat recovery from refrigeration
The choice of heat source depends on several factors like availability, level of acceptable investment, operationalcosts, security of supply, environmental considerations, among other.

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ENERGY SYSTEMSHEATINGIIHF Guide to sustainable ice arenas
2022
Such heat recovery solution
from refrigeration isequivalent to any other heatsource like gas, oil boiler, etc.

recoveryfrom modern
refrigeration
makessuch systems
a 2-in-1solutionsas heating.
they provide both cooling and heating.
Figure 36. HeatFigure
recovery36.
fromHeatmodernrefrigeration
makes such
systems a 2-in-1
solutionsas they provide
bothcooling and

The refrigeration system of an ice rink produces excess heat during its operation. It is therefore vital to
The refrigeration
systemof byanimplementing
ice rink produces
heat
during its
operation.
It is therefore vital to address theaddress the waste
heat utilization
properlyenergy excess
recovering
measures.
Comparedto anyother heat source
the most economical
environmentallyenergy
friendlyrecovering
performance.
wasteit offers
heat utilization
properly andby implementing
measures. Compared to any other heat source
6.2.3

it offers
the most economical and environmentally friendly performance.
Systemsolutions

Heat recovery from a refrigeration system can be implemented in both new and existing ice rink facilities.
6.2.3
Systemsolutions
There are a few
key principles
to follow
in order to utilise the heat recovery efficiently.

Heat recovery from a refrigeration system can be implemented in both new and existing ice rink facilities. There are

The design of a modern heat recovery system, which separates an ice rink from traditional facilities, is donea few key principles to follow in order to utilise the heat recovery efficiently.
by following what is referred to as the “waterfall concept”. The idea behind the concept is to extract heat tovarious heating systems in temperature steps, where the heating system with the highest temperature
The design of a modern heat recovery system, which separates an ice rink from traditional facilities, is done bydemand comes first and others with lower temperature demands follow. This concept should provide lowest
following
whatwhichis referred
to asfromthea“waterfall
concept”.
The –idea
behindthe isconcept
is to extract heat to various
possible returntemperature
is beneficial
heat recovery
point of viewespecially
if CO2usedheatingsystems in temperature steps, where the heating system with the highest temperature demand comes firstin the refrigeration
system.

and others with lower temperature demands follow. This concept should provide lowest possible return temperature

Figure 38 shows an example of an ice rink heat recovery system, where the temperature profile is tailored tobeneficial
froma heatrecoveryof view– especially
if CO2is waterfall
used in the refrigeration system.
the demandswhichof theisfacility
as wellas thepropertiesof point
R744-based
refrigeration
system.
The
concept has the inherent advantage that it cools the primary loop to the lowest possible return temperature,
Figure 38 shows an example of an ice rink heat recovery system, where the temperature profile is tailored to theresulting in an optimized heat recovery system for the ice rink.

demands of the facility as well as the properties of CO2 refrigeration system. The waterfall concept has the inherent
advantage that it cools the primary loop to the lowest possible return temperature, resulting in an optimized heatrecovery system for the ice rink.

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ENERGY SYSTEMSHEATINGIIHF Guide to sustainable ice arenas
2022

Figure 37. Groups of accumulator tanks with coils for tap water pre- and post- heating.
Figure 37. Groups of accumulator tanks with coils for tap water pre- and post- heating.

Those demands can then be gathered in bigger group of temperature level and connected to groups of water
Those demands can then be gathered in bigger group of temperature level and connected to groups of water
accumulators(Figure 37) to store the heat recovery production over time and adapt to the fluctuations inaccumulators (Figure 37) to store the heat recovery production over time and adapt to the fluctuations inheat available.
heat available.

Figure 38. Principle overview
of aPrinciple
refrigeration
recoveryand
system(Illustration
EKA). by EKA).
Figure 38.
overviewandof aheatrefrigeration
heat recovery
systemby(Illustration

Backup heating systems are needed when the heat recover cannot cover the demand or during off-season.

figure above a so called “false load” is applied where a geothermal storage is used to supply heat to
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ENERGY SYSTEMS
DEHUMIDIFICATION

Backup heating systems are needed when the heat recovery cannot cover the demand or during off-season. In the
figure above a so called “false load” is applied where a geothermal storage is used to supply heat to the refrigeration/heat pump system during peak loads or off-season operation. More commonly any of the traditional sources may
be used as mentioned above.

6.3.

ARENA ROOM DEHUMIDIFICATION

Humidity control is very important function to take account in ice rinks. To acquire optimum conditions in
an ice rink a dehumidification function is required, not only to achieve best ice quality but also to provide
a good indoor climate for people as well as the building structure.
Ice rinks have a large cold surface and condensation will occur when warm and humid air enters the building
through doors and other openings. Condensation may form on any cold surface if it is colder than the so-called dew
point. Such surfaces are obviously the ice but potentially also the ceiling or parts of the building structure facing theice, due to the radiation heat transfer with the ice. If the climate in the ice rink space is too humid, corrosion andmould growth may occur which leads to an unpleasant and potentially unhealthy indoor climate for the occupants.

Mold!

Fog!

Condensation on Glass!
Figure 39. Moisture problems are known in many ice rinks. Solution to keep the indoor humidity at acceptable level must be used.

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ENERGY SYSTEMS
DEHUMIDIFICATION

6.3.1

Selection of dehumidification technology

Two types of dehumidification technologies are the most commonly used in ice rinks – sorption and refrigerationIIHF Guide to sustainable ice arenas
based.
2022
Guidesustainable
ice arenas
Sorption type of dehumidifier system are the most common types in IIHF
Nordicicetorinks,
and theyare designed
2022
often
means ofaheat
generatedfromwithinelectrical
produceheat fromis often
andreactivatedcontrolled by
to maintain
constant
dew point
the heaters.
building. To
In somemarketstheseelectricity
systemsarepractical
but not
the best
way tofrom
use theenergyheaters.
– provided
you haveheat
an alternative.
In anisicepracticalrink but
reactivatedbynecessarily
means
heat
generated
electrical
To produce
often reactivatedbyofmeansofheat generated
from electricalheaters.
To producefrom
heatelectricity
from electricity
is
there
is
plenty
of
waste
heat
that
may
be
used
for
such
purposes
which
is
shown
in
Figure26
fromChapter
notpracticalnecessarily
the
best
way
to
use
the
energy–provided
you
have
an
alternative.
In
an
ice
rink
there
is
plentybut not necessarily the best way to use the energy – provided you have an alternative. In an ice rinkof waste
6.1.2.2.
heat
thatismay
be of
used
for heatsuch that
purposes
which
in Figure which
26 from
Chapterin6.1.2.2.
thereplentywaste
may beusedisforshownsuch purposes
is shown
Figure 26 from Chapter
6.1.2.2.

Figureprinciple
40 The working
principle
sorption typeof anddehumidifier
Figure 40 The workingof a sorption
type of adehumidifier(left)
unit (right).(left) and unit (right).
Figure 40 The working principle of a sorption type of dehumidifier (left) and unit (right).

The other dehumidification method is refrigeration-based which essentially is based on the condensation
otherdehumidification
methodis refrigeration-basedwhichessentiallybasedonon
condensation
TheTheotherdehumidification
methodis refrigeration-basedwhichessentiallyis isbased
thethecondensation
principle
principle where a cold surface condensates the moisture in the air. These systems use either a separate
principle
where
a
cold
surfacecondensates
themoisture
in
the
air.
These
systemsuse
eitheraseparate
where a cold
surfacecondensates
the moisturein thefrom
air. These
refrigeration
systemor thecold secondaryrefrigerant
the icesystems
rink. use either a separate refrigeration system
refrigeration
systemorthecoldsecondaryrefrigerant
from
the
ice
rink.
or the cold secondary refrigerant from the ice rink.

Figure 41 The working principle of a refrigeration type of dehumidifier.
Figure 41 The working principle of a refrigeration type of dehumidifier.

TABLE OF CONTENTS Figure 41 The working principle of a refrigeration type of dehumidifier.

The disadvantage with refrigeration-based dehumidification is that the air can only be dried to a certain limit

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ENERGY SYSTEMS
DEHUMIDIFICATION

The disadvantage with refrigeration-based dehumidification is that the air can only be dried to a certain limit –typically to a dew point close to 0°C. This is the level that is actually required in the arena room so having this being
produced in the dehumidifier is not sufficient. To provide an acceptable climate in the arena room therefore requiresvery large air flows through the dehumidifier, which will be very costly from a fan power energy point of view.
Another drawback is the inefficient energy usage with this type of technology for dehumidification purpose.
In the summer, when there is plenty of heat available from heat recovery, it is cheaper to operate sorption
type dehumidifier than a refrigeration-based equivalent (NERIS 2018).

6.3.2

System solutions

The sorption dehumidification method has proven to be the most suitable technology for ice rinks. It can remove
moisture from air in the subzero dew point humidity range without performance issues, like frost formation, andit does not require as high air volumes as the refrigeration-based method. The majority of consumed energy ina sorption dehumidifier is used to heat the reactivation air, and that is where the highest saving potential also lies
since it can be coupled with “free” heat released from the refrigeration system. The challenge, however, is achievinga sufficient amount of the high temperature level that is required for the reactivation process.

Figure 42. Sorption based dehumidification that utilizes the heat recovery from refrigeration, referred to as Generation 2.

Successful application of refrigeration system heat recovery in the dehumidification process has been documented
in both Generation 1 and Generation 2 sorption dehumidifiers. Generation 1 dehumidifiers are more traditional,

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ENERGY SYSTEMS
DEHUMIDIFICATION

where the temperature requirement for the reactivation process is ca 110°C. In this application recoveredheat covers the preheating-range that begins with the ambient air temperature and ends at around 55°C, subsequently followed by the electric heater which further raises the temperature from 55°C to 110°C. Generation 2
dehumidifiers have larger sorption wheels, which lowers the temperature level requirement of the reactivation
process down to 55-60°C. This in turn leads to a higher requirement in fan power, but the sacrifice is made in order
to be able to cover the reactivation process heat demand with recovered heat only.

6.3.3

Dehumidification control

Correct control of humidity level is important to achieve good ice quality and healthy indoor climate in the mostenergy efficient manner. One project (NERIS 2018) documented a 30+ percent energy reduction when changing
the control strategy from the typical relative humidity to dew point based. The dehumidifier should be controlled
to maintain a dew point between 0°C and ca 2°C in typical ice rinks, where indoor temperatures range between
5-10°C. If the dew point is lower than 0°C it operates unnecessarily and if it is higher than 2°C there is an increased
risk of problems related to condensation. Figure 43 illustrates the condensation risk zones and also shows overtime how energy is saved by applying a control strategy based dew point instead of the traditional relative humidity,
where the latter especially tends to “over dry” the arena room when there actually is no dehumidification demand.

Dehumidification energy use per month [MWh]Absolute humidity control principle - Ice Rink A

Relative humidity control principle - Ice Rink B

25,0

20,0

15,0

10,0

5,0

0,0

Jul '15

Aug '15

Sep '15

Oct '15

Nov '15

Dec '15Jan '16

Feb '16

Mar '16

Figure 43. Comparison of energy use between control strategies based on relative humidity and dewpoint/absolute humidity in two ice rinks.

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ENERGY SYSTEMSAIR HANDLING

6.3.4

Energy usage

The performance of both a Generation 1 and a Generation 2 sorption dehumidifier is illustrated in Figure 44.
The results show that in a Generation 1 dehumidifier almost 40 percent of the total energy use is saved in theoperation thanks to the application of recovered heat that otherwise would have been rejected to the ambient air.
For the Generation 2 dehumidifier it can be seen that even with a higher fan power requirement the reactivation
process still requires by far most of the energy, with the additional observation that recovered heat now can cover up
to 100% of the reactivation demand and after that electrical energy is only needed for the fans. A Generation 2
solution can therefore save ca 85% of the total dehumidifier energy consumption.

23,9
37%
40,8
63%

10,0
14%

Heat from heat recovery[MWh]Reactivation heat
[MWh]Eletricity (fans andauxiliaries) [MWh]Electricity (heat andauxiliaries) [MWh]

62,5
86%

Figure 44. Application of recovered heat from a modern refrigeration system in the reactivation process leads to energy savings ofca 40% in Gen 1 and 85% in Gen 2 sorption dehumidifiers.

6.4.

AIR HANDLINGIIHF Guide to sustainable ice arenas
2022

6.4 Air handlingThe
mainpurpose
purposeof ventilation
the ventilation
systemin theis oftentoheatingprovidespace
The mainof thesystem in
the arena
roomarenais oftenroom
to provide
space
and,
when heating and, when needed,needed,
also
fresh
air.
The
ice
arena
ventilationisnormally
dividedinto
different
parts:
the
arena
room
also fresh air. The ice arena ventilation is normally divided into different parts: theandarena room and surrounding
surrounding spaces including locker rooms etc. This is due to the special indoor climate of the arena room,
spacesincluding locker rooms etc. This is due to the special indoor climate of the arena room, which requires its
which requires its own system solution for successful management. In many ice rinks, the arena roomownsystemfor successful
management.
In many
icerecommendation
rinks, the arena
room isventilation
has been integrated
ventilation
has solution
been integrated
together withthe dehumidifier,but thenowadays
tokeep these withseparate.
togetherthe dehumidifier, but the recommendation nowadays is to keep these separate.
Ventilation
supply air
distribution
Process air distribution

Process air inlet
Dehumidifier
Figure 45 Air supplied to different zones in ice arena: Dehumidified air above the ice, and heated air towards the stands. Fresh air

Figure 45. Air supplied to different zones intake
in ice only
arena:
air above the ice, and heated air towards the stands.
whenDehumidified
necessary.
6.4.1

air intakeinonly
when
necessary.
Air Fresh
distribution
arena
room

In order to further maximize the energy efficient climate control of an ice rink, the ventilation and
TABLE
OF CONTENTS
dehumidification distribution systems should be separated in the arena room. Warm ventilation air shouldbe blown towards the spectators where the real heat demand is located, while the dehumidification supply

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ENERGY SYSTEMSAIR HANDLING

6.4.1

Air distribution in arena room

In order to further maximize the energy efficient climate control of an ice rink, the ventilation and dehumidification
distribution systems should be separated in the arena room. Warm ventilation air should be blown towards the
spectators where the real heat demand is located, while the dehumidification supply air should be distributed ina duct centered above the ice. This minimizes unnecessary heat loads towards the ice while also maintaining
optimal comfort levels where they should be.

Figure 46. The ventilation and dehumidification distribution systems should be separated.

In smaller typical sized arena rooms, ventilation/heated air is generally distributed from a single duct
above the stands, with its blowing direction away from the ice. In larger arena rooms the duct can be divided
into two or more groups so that heat is more optimally spread across the stands to maintain adequate comfort
levels regardless of where spectators are seated.

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Figure 47. Textile ducts in an ice rink where dry air is distributed over the ice and “comfort air” to the stands.

6.4.2

Energy efficient principles

Ventilation of the facility shall be based on centralized air handling units (AHU) for the different zones in thebuilding. An AHU can provide ventilation to several rooms with similar air quality and thermal comfort requirements.
The main benefits are related to energy efficiency of central AHU, in addition the optimisation of maintenancecosts is possible because fewer units will require less frequent “hands-on” service staff maintenance,and simpler control adjustments compared to several small ventilation units.

Figure 48. Example of a principle AHU solution for arena room (IV Produkt, 2022).

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ENERGY SYSTEMSAIR HANDLING

Energy efficiency for a ventilation system shall be maximized by designing systems with air-to-air heat recovery andefficient fans. In the EU, for example, it is required that AHU is complying with the minimum performance criteria.
The latest Ecodesign update was in 2018.
••

Heat recovery efficiency, which is expressed as the percentage of energy recovered from theextract air flow:
For rotary heat exchangers, counter-flow heat exchangers or plate heat exchangers > 73%
For run-around coil heat exchangers > 68%
SFP - Specific Fan Power, is expressed as the electrical input required for the fan to supply the airflow.
The lower the SFP, the greater the fan’s energy efficiency:
Internal SFP < 0.8 (considering pressure drop within the AHU)
Corresponding SFP < 1.9 (considering pressure drop within the AHU + distribution duct pressure 200 Pa)

Figure 49. Example of a central air handling unit in an ice arena, the unit is located in a technical room.

Normally the ice rink arena room has little or no need for fresh air ventilation since it consists of a large air volume,
where it takes a long time before the air actually needs to be exchanged due to air quality requirements. Furthermore, such large cold spaces typically have considerable air leaks which reduces the need for active ventilation.
One of the most important reasons for avoiding fresh air is that it brings moisture with it, which will increase thedehumidification demand. This is discussed in Chapter 2 of the guide.

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ENERGY SYSTEMSAIR HANDLINGIIHF Guide to sustainable ice arenas
2022

Measured CO2 concentration in arena room
CO2 concentration in arena air [ppm]

1400
1200
1000
800
600
400
20.02 12:00

21.02 00:00

21.02 12:00

22.02 00:00

22.02 12:00

Figure 50.
Measuredin aicetypicaliceon
rink
on full air recirculation.
Figure 50.. Measured
CO2-levels
in aCO2-levels
typical Nordic
rink Nordic
operatingfulloperating
air recirculation.

It is therefore recommended that the ventilation/heating function in the arena room is normally operated
therefore recommended
ventilation/heating
functionin the load
arenaisroom
is normallyoperated
only
only Itbyisrecirculation,i.e. fresh air thatis notthebrought
in. As a result,the moisture
reducedwhile fresh
airby recirculation,
i.e.throughfresh airis building
not broughtin. As asa result,
the moistureis icereducedwhileactuallyfresh airstill entersstill enters
the ice rinktheenvelope
air leakage
which inload
mostrinks has
been
thetoice
rink throughthe building
envelope
as air leakage
which inin Figuremost ice
found
be enoughto maintainappropriate
CO2-levels,
see example
50. rinks has actually been found to
be enough to maintain appropriate CO2-levels, see example in Figure 50.
Best practice is to have the fresh air supply system controlled by a CO2-sensor, so that necessary fresh air
Bestpractice
is to havethe fresh AairCO2
supplysystem controlled
by appm
CO2-sensor,
so thatnecessary
air would
would
only
be supplied
on demand.
concentrationof > 1500
can be usedas thestartingfresh
signalonly air
be intake.
supplied on demand. A CO2 concentration of > 1500 ppm can be used as the starting signal for freshfor fresh
air intake.

6.5 Arena room lighting

6.5.

ARENA ROOM LIGHTING

Arena
room
lighting
accounts
forforaroundenergy usage
usage inin aa typical
typicalice
icerink.
rink.The
Theradiation
Arena
room
lighting
accounts
around1010percent
percentofofthe
the total
total energy
radiation
fromlighting
the lighting
may contribute
theloadheatof theice asTherewell.areThere
are specificrequirementsfrom themay contributeto the toheat
ofloadthe ice
as well.
specificrequirements
for illuminancefor illuminance
on
the
ice
surface,itvariesbetweendifferent
categories
of
ice
rinks
accordingtolocal
countryon the ice surface, it varies between different categories of ice rinks according to local country standards. In orderstandards. In order to respect illuminance, there are different alternatives available for the type ofto respect illuminance, there are different alternatives available for the type of technology. The lighting efficiency oftechnology. The lighting efficiency of the particular technology is important, i.e., what power is needed tothe particular technology is important, i.e., what power is needed to provide the necessary illuminance.
provide the necessary illuminance.
Many ice rinks still use different types of light tubes such as T5/T8 HF, although the trend is clearly going in the
Many
ice rinkstowards
still useLED,
different
light tubes
such
as in
T5/T8
the old
trend
is clearly isgoingin phased
direction
whichtypes
will ofeventually
take
over
the HF,
ice althoughrinks as theequipment
being
the direction towards LED, which will eventually take over in the ice rinks as the old equipment is beingout. Other types like halogen and metal halogen still exist but much less frequently.
phased out. Other types like halogen and metal halogen still exist but much less frequently.
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ENERGY SYSTEMSLIGHTING

Figure 51. Example of an ice rink with a light tube installation.

In Figure 52 the lighting efficiency of previously typical lighting solutions is presented over time. Halogen lighting have 4000 lighting hours compared to 9000 hours for metal halogen lighting, which is an increase by
125 percent. It is also clear in the figure that the modern types of T5/T8 are not only more efficient than the othertwo but also lasts much longer. As said, however, LED is becoming the main alternative in modern solutions.

Figure 52. Efficiency of different lighting types during their lifespan.

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ENERGY SYSTEMSLIGHTING
IIHF Guide to sustainable ice arenas
2022
Nowadays, LED technology is the best solution on the market, both in terms of quality and efficiency. An
Nowadays, LED technology is the best solution on the market, both in terms of quality and efficiency.
approximation of energy savings with LED technology compared to previous generation technologies is given
An approximation of energy savings with LED technology compared to previous generation technologies is given
in Table 6. As seen between 40 to 75 percent is the possible improvement, and additional benefits ofin Table 6. As seen between 40 to 75 percent is the possible improvement, and additional benefits of considerably
considerably longer LED lifetime has to be taken into account also.
longer LED lifetime has to be taken into account also.
Table 6.

Table 6. Comparison of energy performance in lighting technologies.
Comparison of energy performance in lighting technologies.

Type of Lighting

Efficiency

Expected energy savings
substituting with LED

Halogen12-40 lm/W

50-75%

Fluorescent (T5, T8 bulbs)

40-80 lm/W

20-40%

LED

120+ lm/W

10-15%**replacing old LED with new LED

Figure 53. An
ice rink with a modern LED-lighting system.
Figure 53. An ice rink with a modern LED-lighting
system.

In the case of a new LED-lighting system in a typical sized ice rink, a nominal average light intensity of 600 lux
Incase installedof a new power
LED-lighting
systema typical sized
ice rink, athenominalaverageintensity ofeither
600 lux
andthea totalof ca 10
kW isinreasonable.
Furthermore,
lighting
shouldlight
be controlled
andtotal installed
powerwithof cafixed
10 steps
kW is adjusted
reasonable.
the lighting should
controlledeither by
by a adimmer
alternatively
for Furthermore,game time, training/generaland bepreferably
anotherafordimmer
alternatively
fixednormally
steps adjusted
for gametime,
training/generalpreferably anotherfor ice
ice maintenance.
In withpractice
three steps
are often
used:
0, 50 and 100and% corresponding
to about
maintenance.
In practicenormally
three steps
often areused:
0, 50 and100 % corresponding
to about
0, 5 and0, 5 and 10 kW,
but moresteps according
to aredemandcertainly
recommended
and a steplessdimming
10
kW, but
according
to demandare certainly recommended and a stepless dimming function is by far
function
is moreby farsteps
the most
favourable
solution.
the most favourable solution.

6.6 Building and energy system management
TABLE
CONTENTS
Ice rinkOF
energyand climate controls often appears difficult to manage, as very complex interactions between
the various physical processes happen continuously. It may happen that changing a setpoint in, e.g., airIIHF GUIDE TO SUSTAINABLE ICE ARENAS 2022

65

ENERGY SYSTEMSMANAGEMENT

6.6.

BUILDING AND ENERGY SYSTEM MANAGEMENT

Ice rink energy and climate controls often appears difficult to manage, as very complex interactions between
the various physical processes happen continuously. It may happen that changing a setpoint in, e.g., air handlingsystem, there is a need to adjust a certain setpoint in the refrigeration system.
This leads to a necessity for not only the physical integration but also the control strategy and its implementation.
In addition to that a possibility of monitoring the main functions on-site and remotely plays a key role in the failure
prevention and long-term energy use reduction.

6.6.1

Monitoring and control

A modern ice arena should apply a monitoring and control system, often a Programmable Logic Controller (PLC)
system, which functions as the brain of the facility. In addition to refrigeration, the PLC-system should also control
the functions such as heating, domestic hot water, dehumidification, freeze protection, ventilation, and lighting
systems, as well as potential geothermal storage or heat export functions. By having an externally accessible control system, it becomes possible to synchronize and/or prioritize the energy systems, when necessary, which also
is a prerequisite for the energy optimization process in modern ice rinks.

6.6.2

Visualization

The information that is being measured and calculated by the PLC system shall be visible locally, i.e., in the technical room. The information shall be well structured and user-friendly, so that the technical staff or external experts
are able to verify functions, localize problems, etc., as conveniently as possible. That in turn provides the facility
management with convenient feedback and allows smoother implementation of control changes.

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ENERGY SYSTEMSMANAGEMENT

Figure 54 The control system overview in an ice rink showing the lighting control signal, power and energy.

6.6.3

Energy monitoring

Ice rink further benefit from modern control system that measure the energy usage of the big five energy systems
individually (refrigeration, heating, ventilation, dehumidification, lighting). This allows to optimize the performanceof each individual system further through analysis and also allows for the follow-up of the results after implementedchanges.

Figure 55. Screenshot from an ice rink online monitoring system that includes 1 main and 6 submeters of both heat and electricity.
It allows to analyse and optimize the systems with high accuracy.

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67

WATER
MANAGEMENT

A modern control system should also be able to optimize the performance of the energy systems in the ice rinks
based on parameters such as energy use, temperature, humidity etc. Furthermore, the control system must log
all the data so that it can be analyzed for further optimization or error investigations. Ease of access to the control
system is also recommended, e.g. by having it connected to the internet, whichIIHF
allowsremoteaccess for operational
Guide
to sustainable
ice arenas
staff as well as service companies.
2022

7 Sustainable water management

7

SUSTAINABLE WATER MANAGEMENT

An ice rink uses vast amounts of water and 2–3 million litres per year is often the case in a single sheet ice
An iceuses vast
water litresand 2–3
millionlitresper yearis oftenthe case in a water
single on
sheet
arena
of rinka typical
size.amounts
About 1ofmillionof thetotal
amountis usedas resurfacing
theiceicearena
sheet
a typicalthe
size.iceAbout
1 million litres of the total amount is used as resurfacing water on the ice sheet to maintain
to ofmaintainquality.
the ice quality.

Potential energy savings can be achieved by lowering the water consumption in an ice arena. This can be
Potential
energy savings
can beachieved
by lowering
the bywater
consumption
in maintenancean ice arena. Thiscan beifdone
done
by optimising
the waterflow
in showers
and also
reviewing
the iceroutines,
thereby optimising the water flow in showers and also by reviewing the ice maintenance routines, if there e.g. ise.g. is a possibility to reduce the frequency in ice resurfacing or the amount of water used.
a possibility to reduce the frequency in ice resurfacing or the amount of water used.

Figure 56. Resurfacing water account for approximately 1 mil litres per year and ice sheet.

Figure 56. Resurfacing water account for approximately 1 mil litres per year and ice sheet.

Lately,however,water
water recycling
recycling has
has gained
gained interest.
interest. This
Lately,however,This does
doesnot
notnecessarily
necessarilylead
leadtotosavings
savingsininenergy
energycosts
costs
itselfbut
minimizestheamount
of
fresh
water
that
is
needed
in
the
ice
rink.
As
mentioned
earlier,resurfacing
water
itself but minimizes the amount of fresh water that is needed in the ice rink. As mentioned earlier, resurfacing
represents
a significant
portionof the oftotal
and by applying
recycling
this function,water
represents
a significant
portionthewater
totalconsumption,water consumption,and by water
applying
waterinrecyclingin thisthewater
management
of
the
ice
arena
can
be
improvedsignificantly
to
make
it
more
sustainable.
function, the water management of the ice arena can be improved significantly to make it more sustainable.

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WATER
RECYCLING

Figure 57. By recycling the resurfacing water from the melting pit, the water management of an ice arena can be significantly improved.

The first step to recycle the water is to have a melting pit function which collects the snow and melts it backto liquid water. After that the treatment and recycling process can start.

7.1.

RESURFACING WATER RECYCLING

In recent years, several European countries have suffered from water shortages, where the cause typically has
either been unusually low groundwater levels or that waterworks were close to their maximum technical capacities
and could not cover the increasing water needs. Authorities have therefore occasionally had to introduce restrictions
on water use and sometimes this has hit ice rink operations.
As stated above, a typical ice rink use about 1 million litres of water per year and ice sheet, for resurfacing
to maintain the ice quality. The ice quality is regularly updated by having the ice resurfacer scrape off the
topmost part of the ice layer, which is then dumped either outside the ice rink or into a melting pit connected to thefacility's sewer, and then replace the scraped off part with resurfacing water which freezes and becomes the“new” topmost layer of the ice sheet. Figure 58 shows how the process is done in most ice arenas, indicating thatnew fresh water is needed for each resurfacing.

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WATER
RECYCLING

Figure 58. Classic melting pit function without water recycling.

Nowadays, there are opportunities to recycle this amount of water from the ice that is scraped off and reuse it
in the resurfacing process without deteriorating the quality of the ice. This will potentially save up to the full
1 million litres of water, which creates benefits for the ice rink's operating economy, for society and for the environment.
Heat recovery from the cooling system can be used both to melt the snow and heat the resurfacing water, implyingthat additional heating costs can be avoided.
Figure 59 shows each stage of the water recycling process in the resurfacing (or melting pit) function. The main
addition is a filtering function to maintain the water quality so it can be reused for resurfacing. There are different
kinds of filters which can be used. Some technologies are listed below as examples, but will not be further discussed
within the context of this guide:
•
•
•
•
•

Reverse osmosis
Sand filters
Gravel filters
Carbon filters
Membrane filtration

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CASE STUDIESFACILITY

Figure 59. Water recycling applied in melting pit function.

The filtering process also helps making the water safer for visitors. By removing micro-organisms from thewater and making it clean, complications due to infections in case of injury on the ice is further minimized.
Nevertheless, the water should not be mixed with potable and/or shower water. Even if the water is clean after
the filtration process, it still should be seen as greywater. The recycled resurfacing water should therefore
have its own specific tank-filling system to keep the water in a closed loop.

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CASE STUDIESFACILITY
IIHF Guide to sustainable ice arenas
2022

8 Case studies

8

CASE STUDIES

8.1 Facility case studies

This chapter looks into case studies on a facility-basis, i.e. individual ice arenas where each have been subject
to a number of measures and the changes in total performance is are discussed.

8.1.

FACILITY CASE STUDIESThis chapter looks into case studies on a facility-basis, i.e. individual ice arenas where each have been subject
Ice rink 1 - Gimo (Sweden)
to a number of measures and the changes in total performance is are discussed.

8.1.1

The8.1.1
municipalityof Östhammar
Sweden(Sweden)
wanted to lead by example and apply the most environmentallyIcerink 1 -inGimo
friendly technology in the renovation of Gimo ice rink. In this system the ice rink refrigeration is combined
The municipality of Östhammar in Sweden wanted to lead by example and apply the most environmentally friendly
with a heat pump function and geothermal storage. The facility used to depend on district and electric
technology
in thepurposes,
renovation
Gimo
ice rink. Inonthis
systemthe icerinkheating
for its heating
but it ofis now
self-sufficientthe heatrecoveredfromtherefrigeration
refrigeration is combined with a heat pumpsystem.
function and geothermal storage. The facility used to depend on district and electric heating for its heating purposes,

but it is now self-sufficient on the heat recovered from the refrigeration system.
Energy consumption per season - Gimo
Electricity

District heating

1000

MWh/season

800

600

400

200

0

2009-10

2010-11

2011-12

2012-132014-152015-16

2016-172017-18

2018-2019 2019-2020

BeforeAfterPrimary
Refrigerant

Ammonia

CO2

Secondary
Refrigerant

Calcium
Chloride

CO2

The ice rink became the first of its kind in Europe, where the outstanding results together with its growing reputation
have sparked the concept “the ice rink of the future”.
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CASE STUDIESFACILITY
8.1.2

IIHF Guide to sustainable ice arenas
2022

Ice rink 2 - Testebovallen (Sweden)

This facility consists of two ice sheets (ice hockey and curling in separate buildings) and a sports hall. Before

8.1.2
Ice rink
2 - refrigeration
Testebovallen(Sweden)interventions,a R404A
systemwas used. The heating demand was mainly covered by districtThisfacility
consistsof two CO
ice2 sheets(ice hockey
curling
and a sports
hall. Before
refrigeration
systemand
replacedtheinoldseparate
one. Thebuildings)
existing secondary
circuits
heating.
In 2015,an indirectinterventions,a R404A
refrigeration
systemwas used.
Thetheheatingdemandmainly covered by district heating.
were reused andretrofittedwith aquaammonia,
reducing
pumping
powerwasdemand.
In 2015, an indirect CO2 refrigeration system replaced the old one. The existing secondary circuits were reused
and retrofitted with aqua ammonia, reducing the pumping power demand.

Energy consumption per season - Testebovallen
Electricity

District Heating

1200

MWh/season

1000
800
600
400
200
0

2013-142014-152015-16

2016-172017-18

2018-19

BeforeAfterPrimary
Refrigerant

R404A

CO2

Secondary
Refrigerant

Calciumchloride

AmmoniaWater

The new system provides a new complete one-stage heat recovery function with a constant 60°C forward
temperature. A new sorption dehumidifier utilizes part of the recovered heat for reactivation, lowering its energy
consumption.
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IIHF GUIDE TO SUSTAINABLE ICE ARENAS 2022

IIHF Guide to sustainable ice arenas
2022

CASE STUDIESFACILITY
8.1.3

73

Ice rink 3&4 - Bahcohallen (Sweden)

Bahcohallen was a typical single sheet ice rink, with a heated arena room. An ammonia refrigeration unit
wasconnected
a brinecircuitin the rink floor.(Sweden)
In 2016 a new CO2 system was installed to replace ammonia,
8.1.3
Icetorink
3&4- Bahcohallenwithdirect expansion.
additional
indoorice sheetlocatedin aabrand-new
building
adjacent
to the existing
Bahcohallen
was aAntypicalsinglesheet
ice rink,withheated arenaroom.
An ammonia
refrigeration unit
icewasrinkconnectedcompleted tothearenovationin2017.
brine circuit in the rink floor. In 2016 a new CO2 system was installed to replace ammonia,

with direct expansion. An additional indoor ice sheet located in a brand-new building adjacent to the existing
ice rink completed the renovation in 2017.

Energy consumption per season - Bahcohallen
Electricity

District Heating

1800
1600
MWh/Season

1400
1200

+10%

1000
800
600
400
200
0

2015-2016
Old ice rink

2017-2018
Two new ice rinks

2018-2019
Two new ice rinks

BeforeAfterPrimary
Refrigerant

Ammonia

CO2

Secondary
Refrigerant

Brine

CO2

The new ice sheet was connected to the unit at the beginning of the season 2017-2018. The CO2 system is now
able to run two ice sheets with an energy consumption that is only 10% higher than what the previous ammonia
system needed when running one ice sheet. Almost no district heating is utilized.
65

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CASE STUDIESFACILITY
8.1.4

IIHF Guide to sustainable ice arenas
2022

Ice rink 5 - Eksjö (Sweden)

8.1.4
rink of5 one- Eksjö(Sweden)
This facilityIce
consists
ice sheet.
Before interventions, an ammonia refrigeration system was used. The

This
facility
consistsof oneice bysheet.
Beforeinterventions,an COammoniarefrigeration
system was used.
system replacedheatingdemandwas mainly
covereddistrictheating.
In 2019, a direct
2 refrigeration
the old
one. Theold icewas
sheet
has been
replacedby a newconcrete
floor withcopperpiping.
The
heatingdemandmainlycoveredby district
heating.
In 2019,a directCO2
refrigeration system replaced
the old one. The old ice sheet has been replaced by a new concrete floor with copper piping.

Energy consumption per season - Eksjö
District Heating consumption [MWh]Electricity consumption [MWh]

1000
900
800

MWh/season

700
600
500
400
300
200
100
0

2016-172017-18

2018-192019-20

2020-21

BeforeAfterPrimary
Refrigerant

Ammonia

CO2

Secondary
Refrigerant

Calciumchloride

CO2

The new system provides a new complete two-stage heat recovery function with a constant 70°C forward
temperature. A new sorption dehumidifier utilizes part of the recovered heat for reactivation, lowering its energy
consumption.
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CASE STUDIESFACILITY
8.1.5

IIHF Guide to sustainable ice arenas
2022

Ice rink 6 - Pirkkala (Finland)

8.1.5
rink of6 -onePirkkalaThis facilityIce
consists
ice sheet.(Finland)
Before interventions, an R404A refrigeration system was used. The
This
facility
consistsof onecovered
ice sheet.
Beforeheating.
interventions,an minimize
R404A refrigeration
systemused. The heaheating
demandwas mainly
by electric
In order tocosts, the arena
roomwaswas not
heated,whichwaslead mainly
to regularcomplaints
from visitors
regardingting
demandcoveredby electricheating.
In ordercomfort.
to minimize costs, the arena room was not heated,which lead to regular complaints from visitors regarding comfort.
In 2020, an indirect CO2 refrigeration system replaced the old solution and was connected to the existingrink
floor whichuses Freezium
as secondary system
refrigerant.
In 2020,an indirect
CO2 refrigeration
replaced the old solution and was connected to the existing

rink floor which uses Freezium as secondary refrigerant.
900- New CO2 refrigeration systemwith heat recovery technology- Control not optimized yet- Heated arena room

- Traditional HFC refrigeration system- Heated arena room
800

700

- Traditional HFC refrigeration system- Non-heated arena room

- CO2 system control
according to EKA
design requirements- Heated arena room
- Sustainable andcomfortable ice rink!

- New LED lighting
in arena room

600

MWh

500

400

300

200

100

0

Reference

TABLE OF CONTENTS

2016-20172017-20182018-201967

2019-2020

2020-2021

2021-2022

BeforeAfterPrimary
Refrigerant

R404A

CO2

Secondary
Refrigerant

Freezium

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76

CASE STUDIESFUNCTION
8.2 Function case studies

IIHF Guide to sustainable ice arenas
2022

This chapter looks into case studies on a function-basis, i.e. how a change in an individual function haschanged its performance.

Refrigerant heat recovery performance – Zinkensdamms IP (Sweden)
The new system 8.2.1
providesa new complete two-stage heat recovery function with a constant 70°C forward
temperature. A new sorption dehumidifier utilizes part of the recovered heat for reactivation, lowering its energy
Power Consumption Cooling & Heating
consumption.
Compressor

Pumps and fans

Today the ice rink arena room is heated and spectators can be found sitting comfortably in the stands in thesustainable ice rink.
600
MWh/year

8.2.

IIHF Guide to sustainable ice arenas
2022

FUNCTION CASE STUDIES

400

This chapter looks into case studies on a function-basis, i.e. how 200
a change in an individual function has changed
its performance.

on a function-basis, i.e. how a change in an individual function has

In this project, two different solutions for suppling cold and heat to 0a Bandy and to an Ice Hockey arena, locatedCO2 with
NH3 withheat recovery
heat recovery
in the center of Stockholm, Sweden, were assessed.

performance – Zinkensdamms IP (Sweden)

Heat available from the refrigeration system
Power Consumption Cooling & Heating
Compressor

400

200

1200

79%

800

400

44%

41%
21%

0

CO2 withheat recovery

NH3 withheat recovery

NH3

1600

MWh/year

600
MWh/year

CO2

Pumps and fans0Heat above 40°C

14%Heat between
40°C and 25°C

Heat under 25°C

Heat
systemThe available
aim of thefrom
studythewasrefrigeration
to identify thebest solution in terms of system layout and refrigerant. The calculationshows that difference in terms of power consumption between CO2 and ammonia is negligible.
CO2

MWh/year

1600

1200

Since, CO2 has more heat available at high temperature. Considering that 2/3 of the heat in ice rinks is consumed
at temperatures higher than 40°C, CO2 was chosen as the best
68 solution.
79%

800

400

44%

41%
21%

0

NH3

TABLE
OF40°CCONTENTS
Heat
above
Heat between
40°C and 25°C

14%Heat under 25°C

IIHF GUIDE TO SUSTAINABLE ICE ARENAS 2022

IIHF Guide to sustainable ice arenas
77
2022

CASE
STUDIES
8.2.2 Dehumidification with Full Heat Recovery – Testebovallen (Sweden)
FUNCTION

IIHF Guide to sustainable ice arenas
A common best practice in ice rinks is to use absorption-based dehumidification systems, to take advantage
2022
of the heat recovery from the refrigeration system. The full heat recovery solution is characterized by a
8.2.2 low
Dehumidification
with Full Heat
Recovery– Testebovallen
relatively
reactivation temperature(55-60°C).
Therefore,
the heat (Sweden)
recovered from the refrigeration
cycle is Dehumidification
enough to heat the reactivation
air. Recovery – Testebovallen (Sweden)
8.2.2
with Full Heat

A commonbestbest
practicein icerinks
adsorption baseddehumidification
dehumidificationsystems,
systems,
to takeadvantage
A commonpracticein icerinksisisto
to useuse absorption-based
to takeadvantageof theofheat
recoveryfrom fromthe refrigeration
system.
The fullsolution
is characterized
by a relatively
the heatrecoverythe refrigeration
system.
Theheatfull recovery
heat recovery
solution
is characterizedby a
low reactivation
temperature(55-60°C).
Therefore,theheat
recoveredfromtherefrigerationcycle
isenoughrelatively low reactivation temperature (55-60°C). Therefore, the heat recovered from the refrigeration
to heattheisreactivation
air. the reactivation air.
cycle
enough to heat

Heat recovered from the refrigeration cycle can be utilized for dehumidifying the air. In the sport facility called
Testebo, Sweden, the solution was implemented where ca 85% of the energy cost for dehumidification can be covered by the heat recovery. The estimated energy saving is equivalent to 5000 - 6500 Euros/year.

Testebo, Energy Used for Dehumidification
10 MWh/year

Testebo, Energy Used for Dehumidification
10 MWh/year

85% Recovered Heat (free)
15% Electricity
85% Recovered Heat (free)
15% Electricity
62.5 MWh/year

62.5 MWh/year

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78

CASE STUDIESFUNCTION

8.2.3

Climate Control of large arenas – Scaniarinken (Sweden)

In medium and large arenas, ensuring comfort for the spectators while providing dry and cold air on the ice
sheet can be very challenging. The presence of areas with different comfort levels, such as restaurants,
can complicate the picture further.
IIHF Guide to sustainable ice arenas
2022

8.2.3

Climate Control of large arenas – Scaniarinken (Sweden)

One of these examples is Scaniarinken, an ice hockey stadium in Sweden with capacity of 6200 spectators. Before
interventions there was a temperature difference of 8°C between the top and the bottom of the stands. Nowadays,
this temperature difference is reduced to less than 2°C only.
The system solution, as indicated in the pictures, is mainly based in dividing the air distribution in “rings”,
where the innermost is purely used by the dehumidification system and the rest for ventilation / air heating.

Energi & Kylanalys ©

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79

SAVINGSINVESTMENT

9QUICK SAVINGS IN EXISTINGICE ARENAS –IIHF Guide to sustainable ice arenas
2022
NO/LOW INVESTMENT

Quick savingsin existing
arenassolutions– No/Low
While thelong-term ice
sustainable
will investment
require some investments, as discussed in this guide, many ice

hile the long-termsustainable
solutionsachieve
will require
somequickinvestments,
discussedin thisguide, manyto
icetheir existing systems with little
arenascan alreadysomesavingsas bymakingadjustments
enas can alreadyachievesomequick
savingsbymakingadjustments
totheirexisting
systems
withlittleto arena more sustainable, since it
to no capital cost. This is often a good first step in the process of making the iceo capital cost. This is often a good first step in the process of making the ice arena more sustainable, sinceengages staff and decision-makers into making changes happen.
engages staff and decision-makers into making changes happen.

Figure 60. Quick savings can often be achieved in existing ice arenas by adjusting and/or optimizing the operation of existing solutions.
Figure 60. Quick savings can often be achieved in existing ice arenas by adjusting and/or optimizing the operation of existing
Below a number of typical quicksavings tips are listed, these are further treated in the document Quick Ice Arena
solutions.

Energy Savings, which is available separately via IIHF. It should, however, be stressed again that the biggest

elow a number of typical quick savings tips are listed, these are further treated in the document Quick Ice
savings
by farare achievedby retrofitting
ice arenas
accordingto thisguide.
ena Energy Savings,
which
is available
separately
via IIHF. It should,
however,be stressed
againthat theggest savings by far are achieved by retrofitting ice arenas according to this guide.
•
•
•
•
•
•
•
•
•
•

•
Quick tip #1 – Reduce arena room air temperature
Quick tip •#1 – Reducearenatiproom
temperature
Quick#2 –airIncrease
ice temperature during no activity
Quick tip •#2 – Increase
ice
temperatureduringactivity
Quick tip #3 – Optimize norefrigeration
system operation
Quick tip #3 – Optimize refrigeration system operation
Quick
tip #4 –performance
Optimize condenser performance
Quick tip •#4 – Optimize
condenser
Quick tip •#5 – Optimize
pump
Quick
tip control#5 – Optimize pump control
Quick tip •#6 – Optimize
dehumidifiercontrol dehumidifier control
Quick tip #6 – Optimize
Quick tip #7 – Optimize ice thickness
Quick#7 – Optimize
ice thickness
Quick tip •#8 – Optimize
ice tip
resurfacer
use
Quick tip •#9 – Optimize/reduce
fresh
air intake ice resurfacer use
Quick tip #8– Optimize
Quick tip •#10 – Separate
theclimatezones
Quick tip #9 – Optimize/reduce fresh air intake•
Quick tip #10 – Separate the climate zones
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SUPPLIERSCONSULTANTS

10REFERENCES

Title page photo by Andreas Bobert.
ASHRAE. 2014. ASHRAE Handbook - Refrigeration. Atlanta: American Society of Heating,
Refrigeration, and Air-conditioning Engineering, Inc.
Danfoss. (N.D). Transcritical Refrigeration Systems with Carbon Dioxide (CO2). Danfoss A/S
IIHF. 2016. IIHF Ice Rink Guide. Zurich.
Karampour, M., 2011. Measurement and modelling of ice rink heat loads. KTH
Kaya, R., 2017. Energy usage in ice rink resurfacing. KTH
Kilberg, B. 2020. Aqua Ammonia as Secondary Fluid in Ice Rink Applications. Stockholm, KTH.
Makhnatch, P. 2018. Refrigerants and refrigerant mixtures. Stockholm.
NASA Earth Observatory. 2012. Watching the Ozone Hole Before and After the Montreal Protocol.
Opetusministeriö. 2007. Liikuntapaikkajulkaisu 92: Jäähallien lämpö- ja kosteustekniikka (in Finnish: Ice rinktechnology). Helsinki: Rakennustieto.
Rogstam et al., 2016. Ice rink of the future - evaluation of energy and system solutions. EKA
Rogstam, J. 2016. Evolution of CO2 refrigeration systems in ice rinks. ASHRAE Journal.
Rogstam, J., Bolteau, S., Grönqvist, C. 2017. Cooling and heating ice rinks with CO2. ASHRAE Journal.
Rogstam et al. Neris – del 1-5, 2018. Fukthantering i ishallar (in Swedish: Moisture handling in ice rinks– 5 reports). KTH / EKA.
Stoppsladd. 2009-2014. A field study project of ice rink performance together with the Swedish Ice Hockey
Association (SIHA). (In Swedish)Yousif, S., & Douglah, A. 2017. Hur skall en ishallsvägg byggas? (In Swedish: Ice rink building envelope) KTH,
Stockholm.
NERIS project part 1 -5, 2018. Evaluation and Renovation of Ice halls and Swimming halls. KTH, Stockholm.
More studies available via EKA website www.ekanalys.se

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