7

- i C HAPTER 7. ENERGY USE ANALYSIS

TABLE OF CONTENTS

7.1 INTRODUCTION

................................ ................................ ................................ ........... 7

- 1

7.2 BUILDING SAMPLE

................................ ................................ ................................ ..... 7

- 2

7.3 RESIDENTIAL BOILER E NERGY CONSUMPTION

................................ ................. 7

- 5

7.3.1 Space Heating Fuel Consumption

................................ ................................ .................... 7

- 6

7.3.1.1 Determination of Space Heating Burner Operating Hours (BOH SH )

............ 7

- 6

7.3.1.2 Determination of Equipment Sizing

................................ ............................ 7

- 10

7.3.2 Water Heating Energy Consumption

................................ ................................ ............. 7

- 10

7.3.3 Electricity Consumption

................................ ................................ ................................ 7

- 11

7.4 SUMMARY OF ENERGY US E RESULTS

................................ ................................ . 7

- 13

7.4.2 Standby Energy Consumption Results for Boilers

................................ ........................ 7

- 15

LIST OF TABLES

Table 7.1.1 Residential Boiler Product Classes Analyzed

................................ ...................... 7

- 1

Table 7.2.1 Selection of RECS 2009 Records for Boilers (Replacements)

............................ 7

- 3

Table 7.2.2 Selection of RECS 2009 Records for Boilers (New Construction)

..................... 7

- 4

Table 7.2.3 Selection of CBECS 2003 Records for Boilers (Replacements)

......................... 7

- 4

Table 7.2.4 Selection of CBECS 2003 Records for Boilers (New Construction)

.................. 7

- 5

Table 7.3.1 Range of Original Heating Energy Use based on RECS 2009 and CBECS 2003 data for Each Boiler Product Class, MMBtu/year

................................ ...... 7

- 7

Table 7.3.2 Adjustment to AFUE Based on RWT Application

................................ .............. 7

- 8

Table 7.3.3 Range of Adjusted Heating Load for Each Boiler Product Class, MMBtu/year

................................ ................................ ................................ ......... 7

- 9

Table 7.3.4 Range of Baseline Boiler Heating Annual Operating Hours for Each Boiler Product Class, hours

................................ ................................ ................ 7

- 10

Table 7.3.5 Range of Standby Hours for Each Boiler Product Class, Hours

........................ 7

- 12

Table 7.4.1 Average Annual Energy Consumption and Savings for Residential Boilers

.... 7

- 14

Table 7.4.2 Aver age Annual Standby Consumption and Savings for Residential

Boilers

................................ ................................ ................................ ................ 7

- 157

- 1 CHAPTER 7. ENERGY USE ANALYSIS

7.1 INTRODUCTION

The purpose of the energy use analysis is to determine the annual energy consumption of

residential boilers in use in the United S tates and to assess the energy savings potential of

increase s in annual fuel utilization efficiency ( AFUE )

. In contrast to the U.S. Department of Energy ( DOE ) test procedure, which uses typical operating conditions in a laboratory setting, the energy use analysis seeks to estimate the range of energy consumption of the products in the

field. DOE estimated the annual energy consumption of boiler s at specified energy efficiency levels across a range of climate zones

, building characteristics , and heating applications

.

For the calculation of the energy consumed by residential boilers, DOE considered the energy use associated with providing space heating and domestic water heating in either residential or commercial buildings

. a DOE did not include within the energy use estimates energy used for snow melt systems, poo l or spa heating, or steam or hot water production for industrial or commercial processes. b The energy use analysis provides estimates of the distribution of annual energy consumption for boiler s at the efficiency standard levels

considered.

DOE developed energy consumption estimates for the key product classes listed in Table

7.1.1

. The boilers analyzed utilize gas or oil fuel for heating water or steam and the associated electric energy to power a water pump, a draft inducer, an ignitor, and other auxiliary equipment. Standby energy use is calculated for all product classes mentioned in Table 7.1.1 and also for

electric hot water and electric steam boilers.

Table 7.1.1 Residential Boiler Product Classes Analyzed

Gas

- Fired Hot Water Boilers

Gas

- Fired Steam Boilers

Oil

- Fired Hot Water Boilers

Oil

- Fired Steam Boilers

DOE estimated the energy consumption of boilers in housing units and commercial buildings by developing a building sample for each of the four product classes based on the Energy Information Administration’s (EIA) 2009 Residential Energy Consumption Survey (RECS 2009) and on EIA’s 2003 Commercial Building Energy Consumption Survey (CBECS

a Space heating applications for residential boilers include radiant heating (In

- floor, radiant panels, radiators, baseboard) and force d air using fan coils or central air handlers. Domestic water heating applications for residential

boilers include indirec t water heating, combination equipment, and tankless coil.

b Examples of industrial and/or commercial processes include car washes, steam for dry cleaning, restaurant water heating, manufacturing, etc.7

- 2 2003). 1

, 2 These are the latest available surveys for residential and commercial buildings. c This sample is further described in section 7. 2

.

DOE used the RECS 2009 or CBECS 2003 reported heating energy consumption (based on the existing heating system) to calculate the space heating load of each household or building

. The heating lo ad represents the amount of heating required to keep a housing unit comfortable throughout an average year. In households or building s in which DOE identified that the boiler also serves domestic hot water heating needs, DOE used the REC S 2009 or CBECS 200 3 reported water heating energy (based on the existing heating system) to calculate the water heating load of each household or building.

DOE assigned the energy efficiency of existing systems based on the design of the distribution systems (heating appl ication)

, a historical distribution of energy efficiencies for

boiler s , and data with respect to the age of the existing boiler . In addition, DOE made adjustments based on historical weather data, average return water temperature, projections of

shell effi ciency and building square footage, and for homes that had secondary heating equipment that used the same fuel as the boiler. To complete the analysis, DOE calculated the energy consumption of alternative (more energy

- efficient) products, if they replaced existing systems in each housing unit or commercial building

.

7.2 BUILDING SAMPLE

DOE’s calculation of the annual energy use of residential boiler s relied on data from the Energy Information Administration’s (EIA ) RECS 2009 and CBECS 2003

. 1

, 2 The RECS 20 09

included energy

- related data from 12,083 housing units that represent almost 113.6 million

households. The CBECS 2003 included energy

- related data from 5,215 buildings representing 4.9 million buildings.

The subset RE CS 2009 or CBECS 2003 records used in the analysis met all of the following criteria:

• used a boiler as the main or secondary source of heat;

• used a heating fuel that is natural gas, liquefied petroleum gas (LPG), electricity

, or fuel oil; and

• had a heating energy consumption greater than zero

.

DOE divided the boiler subset into further subsets designed to include households that

use one of the boiler product classes ( Table 7.2.1 and Table 7.2.2 for residential applications and

Table 7.2.3 and Table 7.2.4 for commercial applications ). The new construction sample includes only buildings built after 1990, which DOE believes would have more similar building

c EIA is currently working on the 2013 version of REC S, which is not expected to be available until 2015. Additionally, EIA determined that the 2007 Commercial Buildings Energy Consumption Survey did not yield valid statistical estimates of building counts, energy characteristics, consumption and expenditur es and therefore did not release the majority of the data tables and public use files.7

- 3 characteristics to the new construction buildings in 2020 ( e.g. building insulation, regional

dis tribution of the buildings, and so on ).

The RECS 2009 and CBECS 2003 weighting indicates how commonly each household or commercial building configuration occurs in the general population in 2009 and 2003, respectively. DOE adjusted EIA’s weightings for each RECS 2009 and CBECS 2003 household to create boiler population weights in 2020 by account ing for the fraction of boilers that produce steam compared to hot water, buildings with multiple boilers, and projected growth of the number of boilers by 2020. Appendix 7

- A presents the variables inc luded and their definitions, as well as further information about the derivation of the household and building samples, the adjustments to the boiler population weights, and sampling fractions for each of the four samples (residential (new construction and replacement) and commercial (new construction and replacement)).

To sample between the residential and commercial samples, DO E used the shipments model described in chapter 9 to estimate that 7 percent of residential boiler shipments will be

installed in commercial buildings . To sample between the new construction and replacement

markets , DOE estimated that the new construction market accounts for 20 percent of gas

- fired hot water boilers, 0 percent of gas

- fired steam boilers, 5 percent of oil

- fired hot water boilers,

and 0 percent of oil

- fired steam boilers

.

Table 7.2.1 Selection of RECS 2009 Records for Boilers (Replacements)

Product Class Algorithm No. of

Records RECS

2009 DOE

2020

Number

of

Houses

million Number

of Boilers

million

Gas

- Fired Hot Water Boiler Heating Equipment = Gas Boiler d

Heated Square footage <10,000 sq ft 646 6.05 4.12

Gas

- Fired Steam Boiler Heating Equipment = Gas Boiler

House Built = before 1970
Heated Square footage <10,000 sq ft 471 4.55 0.49

Oil

- Fired Hot Water Boiler Heating Equipment = Oil Boiler
Heated Square footage <10,000 sq ft 4 82 3. 99 2. 63

Oil

- Fired Steam Boiler Heating Equipment = Oil Boiler

House Built = before 1970
Heated Square footage <10,000 sq ft 3 59 3.08 0.31

Electric Hot Water or Steam

Boiler e Heating Equipment = Electric Boiler
Heated Square footage <10,000 sq ft 49 0.49 0.26

d Natural Gas or LPG Boiler.

e The sample is assumed to be the same for both hot water and steam electric boilers7

- 4 Table 7.2.2 Selection of RECS 2009 Records for Boilers (New Construction)

Product Class Algorithm No. of

Records RECS

2009 DOE

2020

Number

of

Houses

million Number

of Boilers

million

Gas

- Fired Hot Water Boiler Heating Equipment = Gas Boiler
Heated Square footage <10,000 sq ft

House Age >= 1990 5 1 0.5 0 0.4 4

Gas

- Fired Steam Boiler NA f 0 0.00 0.00

Oil

- Fired Hot Water Boiler Heating Equipment = Oil Boiler
Heated Square footage <10,000 sq ft

House Age >= 1990 4 9 0. 33 0.2 6

Oil

- Fired Steam Boiler NA 0 0.00 0.00

Electric Hot Water or Steam

Boiler Heating Equipment = Electric Boiler
Heated Square footage <10,000 sq ft

House Age >= 1990 4 * 0.05 0.05

*Note: Used electric boiler replacement sample instead due to the low number of households (4 households does not constitute a representative sample)

Table 7.2.3 Selection of CBECS 2003 Records for Boilers (Replacements)

Product Class Algorithm No. of

Records CBECS

2003 DOE 2020

Number of Building s

million Number

of Boilers

million

Gas

- Fired Hot Water Boiler Heating Equipment = Gas Boiler g

Heated Square footage <10,000 sq ft 2 86 0.2 6 0. 29

Gas

- Fired Steam Boiler Heating Equipment = Gas Boiler
Building Built = before 1970
Heated Square footage <10,000 sq ft 1 93 0.1 9 0. 03

Oil

- Fired Hot Water Boiler Heating Equipment = Oil Boiler
Heated Square footage <10,000 sq ft 7 5 0.1 1 0. 11

Oil

- Fired Steam Boiler Heating Equipment = Oil Boiler
Building Built = before 1970
Heated Square footage <10,000 sq ft 60 0.0 9 0. 01

Electric Hot Water or Steam

Boiler Heating Equipment = Electric Boiler
Heated Square footage <10,000 sq ft 138 0.10 0.13

f DOE assumed that there are no steam boilers in the new construction market.

g Natural Gas or LPG Boiler.7

- 5 Table 7.2.4 Selection of CBECS 2003 Records for Boilers (New Construction)

Product Class Algorithm No. of

Records CBECS

2009 DOE 2020

Number of Building s

million Number of

Boilers

million

Gas

- Fired Hot Water Boiler Heating Equipment = Gas Boiler
Heated Square footage <10,000 sq ft
Building Age >= 1990 31 0.02 0.0 5

Gas

- Fired Steam Boiler NA h 0 0.00 0.00

Oil

- Fired Hot Water Boiler Heating Equipment = Oil Boiler
Heated Square footage <10,000 sq ft
Building Age >= 1990 10 0.02 0.0 2

Oil

- Fired Steam Boiler NA 0 0.00 0.00

Electric Hot Water or Steam

Boiler Heating Equipment = Electric Boiler
Heated Square footage <10,000 sq ft
Building Age >= 1990 24 0.02 0.02

7.3 RESIDENTIAL BOILER E NERGY CONSUMPTION

To c alculate the energy use of residential boilers in each of the product classes , DOE determined the energy consumption associate with space heating, water heating and any auxiliary electrical use during the periods of heating (space and water)

. For the space heating energy consumption determination, DOE estimated the input capacity and burner operational hours of the existing boiler usin g building heating loads and boiler characteristics . For the domestic water heating energy consumption determination, DOE identified the building water heating load and the AFUE of the existing boiler.

The electrical consumption was determined using the burner operating hours associated with space and water heating and individual electrical measurements of all electrical components. Standby electrical consumption was also considered in the electrical ene rgy use. The sum of the space heating, water heating and electrical energy consumptions represents the estimated annual energy use of a sampled boiler. Additional details used for determining the total energy use can be found in the following sections.

T he calculation used for the determination of the total energy use is as follows:

Total Energy Use = FuelUse SH + FuelUse WH + ElecUse Eq. 7.3

. 1

Where:

FuelUse SH = t otal fuel consumption as a result of space heating loads

, FuelUse WH = t otal fuel consumption as a result of water heating loads , and

h DOE assumed that there are no steam boilers in the new construction market.7

- 6 ElecUse = e lectrical consumption of all electrical components

.

7.3.1 Space Heating Fuel C onsumption

The Department ca lculated the annual fuel consumption ( FuelUse ) for each single

- stage boiler using the following formula from the current American Society of Heating, Refrigerating

and Air

- Conditioning Engineers (ASHRAE) test procedure SPC 103

- 2007 section C: i

, j

FuelUse SH = BOH SH × Q IN Eq. 7.3

. 2

Where:

BOH S H = space heating burner operating hours (hr /yr ), and Q

IN = input capacity of existing boiler (kBtu/hr).

DOE derived BOH from the building heating load served by a single boiler. Building heating load was determined from annual fuel consumption for heating reported in RECS and CBECS based on the AFUE of the existing boiler.

7.3.1.1 Determination of Space Heating Burner Operating Hours (BOH SH )

DOE c alculated space heating burner operating hours for a single

- stage boiler are :

BOH SH = BHL BOILER Q Useful Eq. 7.3

. 3

Where:

Q Useful = total useful energy output of the boiler equipment

, including useful heat from auxiliary electrical components (kBtu/hr) , and

BHL BOILER = b uilding heating load served by a single boiler (kBtu/ yr )

.

The total useful energy output ( Q Useful ) includes the output heating capacity of the boiler

as well as useful heat from auxiliary electrical components (such as the electronic ignition, water pump, and power to the burner) during the periods of space heating. S ee appendix 7

- B for more

details.

The annual building

- heating load ( BHL Boiler ) is the total amou nt of heat output from the

boiler that the house or building needs during the heating season. k This includes heat from the

i This formula assumes that the equipment does not have a pilot light, w hich is true for all residential boilers sold after September 2012.

j For two

- stage and modulating equipment this formula includes parameters for the operation at full, modulating, and

reduced load.7

- 7 burner and heat from the other electrical components

. DOE determined BHL Total for each sampled housing unit or building , based on the efficiency of the assigned existing boiler , using the following calculations:

BHL Boiler = � Q YR × AFUE ex

, adj � × Adj

_ Factor ( s )

BoilerCount Eq. 7.3

. 4

Where:

Q YR = annual fuel consumption for heating based on RECS 2009 or CBECS 2003 (kBtu/yr),

AFUE ex,adj = AFUE of the existing boiler ( AFUE

ex ) adjusted for return water temperature l (see appendix 7

- B), Adj_Factor = adjus tment factors (discussed below), and

BoilerCount = number of boilers used to fulfill the building heating load.

Both RECS 2009 and CBECS 2003 report space heating energy use ( Q YR ) for each of the sampled buildings. Table 7.3.1 shows the original RECS 2009 and CBECS 2003 heating energy

use.

Table 7.3.1 Range of Original Heating Energy Use based on RECS 2009 and CBECS

2003 data for Each Boiler Product Cla ss, MMBtu/year

Product Class Min Max Average Percentiles

5% 25% 50% 75% 95%

Gas

- Fired Hot Water Boilers 0.1 4725.4 92.7 21.3 52.7 73.8 104.7 197.7

Gas

- Fired Steam Boilers 0.5 3833.7 98.6 28.3 59.4 79.1 113.7 193.8

Oil

- Fired Hot Water Boilers 0.0 2219.0 93.7 30.2 51.4 71.2 109.7 189.7

Oil

- Fired Steam Boilers 0.0 2219.0 98.1 28.3 50.3 69.4 114.0 216.8

Electric Hot Water Boiler s 0.0 364.3 15.5 3.1 7.7 11.7 19.9 39.5

Electric Steam Boilers 0.0 364.3 15.5 3.1 7.7 11.7 19.9 39.5

The AFUE of the existing boiler ( AFUE

ex ) is determined by matching historical AFUE to

the data to the reported age of the boiler in RECS 2009 or distribution of boiler age for CBECS 2003 buildings. m DOE adjusted the AFUE of existing boilers to reflect the variability of efficiency in various hyd ronic space heating applications. This adjustment is the result of DOE associating a specific space heating application with each sampled household or building. The

k BHL is the load served by a single boiler. DOE made the assumption that some of the building structures would be served by multiple residentially sized boilers based on RECS data, heating load of the building exceeds 300 Btu/h, and/or the application (such as multi

- family and commercial applications).

l Return water temperature represents the average annual return water temperature for the different space heating applications.

m CBECS 2003 does not report the age of the equipment, so DOE created a uniform distribution to estimate the age of the equipment.7

- 8 AFUE of the existing boilers was adjusted up or down depending on the selected return water temperature (RWT) application. Appendix 7

- B provides additional detail regarding the derivation of the adjustment values.

Table 7.3.2 provide s th e adjustment values based on RWT application type. High RWT is applied to 100 percent of non

- condensing boiler installations . For condensing boiler instal lations Low RWT is applied to 100 percent of new construction, 50 percent of replacement buildings

bui lt after 1990

, and to 10 percent of replacement buildings built before 1990. DOE assumes that all other condensing boiler installations would be in High RWT applications.

Table 7.3.2 Adjustment to AFUE Based on RWT Application Low RWT (100 ° F) Medium RWT (120 ° F) n High RWT (150 ° F)

Non

- Condensing Not Applicable As r eport ed

- 0.6 % Condensing + 3% As r eport ed

- 3%

DOE made adjustments to the B HL to reflect the expectation that the buildings in 2020

will have a somewhat different B HL than the buildings in the RECS 2009 and CBECS 2003

boiler sample. The adjustment involves multiplying the calculated BHL for each RECS 2009 or CBECS 2003 buil ding by the building shell efficiency index o based on information from the National Energy Modeling System ( NEMS ) simulation perf ormed for EIA’s Annual Energy Outlook ( AEO 2013 )

. 3 This factor differs for residential and commercial buildings as well as new construction and replacement buildings. The factor applied in the analysis for residential buildings is 0.93 for replacements and 1.03 for new construction, while for commercial bu ildings it ranged from 0.74 to 0.98 for replacements (depending on building type) and 0.89 for new

construction. This means that buildings on average will have lower space heating load compared

to residential buildings in 2009 or commercial buildings in 20 03, except for new construction residential buildings

.

DOE also made adjustments to the BHL TOTAL calculated using heating degree days reported in RECS 2009 and CBECS 2003 for each building, National Oceanic and Atmospheric Administration (NOAA) data by region to reflect historical average climate conditions. The adjustment factor s are calculated using the following equation :

Ad j Factor averag e c limate = HDD 10

_ yr

_ avg HDD bldg

_ 2009 Eq. 7.3

. 5

Where:

n Med ium water temperature of 120 ° F is assumed to be equivalent to the test conditions specified in the DOE AFUE

test.

o The building shell efficiency index sets the heating load value at 1.00 for an average home in 2009 (by type) in

each census division. The v alues listed below represent the change in heating load based on the difference in physical size and shell attributes for homes in the future (which takes into account physical size difference and efficiency gains from better insulation and windows).7

- 9 HDD bldg _200 9 = HDD in 200 9 for the specific region where the housing unit is located, and

HDD 10 _yr_avg = 10

- year average HD D (200 3

– 20 1 2 ) based on National Oceanic and Atmospheric Administration ( NOAA ) data 4 for the specific region where the housing unit is located. p

The adjustment factors for residential buildings range from 0.91 to 1.02 and on average 0.95 for the boiler building sample (i.e., 2009 was in general colder than an the 10

- year average )

. DOE also account for future climate trends based on AEO 2013 HDD projections

. 3

DOE det ermined that some of the sampled buildings used multiple heating equipment with the same fuel as the boiler(s)

, such as a central furnace, wall furnace , room heater, stove, or fireplace. Therefore

, DOE adjusted the calculated BHL when necessary to reflect the use of secondary heating equipment using the same fuel as the boiler(s) . The adjustment factors are calculated using reported survey information fr om both RECS 2009 and CBECS 2003 regarding the fraction of heating that was met by different heating equipment

.

Table 7.3.3 shows the results for the range in adjusted heating load among sample

households and buildings

.

Table 7.3.3 Range of Adjusted Heating Load for Each Boiler Product Class

, MMBtu/year

Product Class Min Max Average Percentiles

5% 25% 50% 75% 95%

Gas

- Fired Hot Water Boilers 0.0 2896.3 61.2 14.2 34.4 49.3 70.8 127.0

Gas

- Fired Steam Boilers 0.3 2160.5 59.9 15.1 35.6 49.6 68.6 118.2

Oil

- Fired Hot Water Boilers 0.0 1604.1 63.5 19.1 34.9 48.3 74.0 128.7

Oil

- Fired Steam Boilers 0.0 1604.1 63.8 17.0 31.9 44.6 74.4 133.8

Electric Hot Water Boiler s 0.0 289.9 8.5 1.2 2.9 7.5 10.3 20.8

Electric Steam Boilers 0.0 289.9 8.5 1.2 2.9 7.5 10.3 20.8

Table 7.3.4 shows the results for the baseline heating boiler operating hours among sample households and buildings.

p The last 10

- year average is used to normalize the HDD values, which is similar to what is done in AEO 2013

.7

- 10 Table 7.3.4 Range of Baseline Boiler Heating Annual Operating Hours for Each

Boiler Product Class, hours

Product Class Min Max Average Percentiles

5% 25% 50% 75% 95%

Gas

- Fired Hot Water

Boilers 0.2 8760.0 515.7 152.4 286.1 412.5 634.6 1082.3

Gas

- Fired Steam Boilers 1.4 8760.0 466.1 127.0 266.7 372.0 562.7 1105.2

Oil

- Fired Hot Water

Boilers 0.1 6383.5 455.8 115.9 268.1 385.4 525.8 1049.6

Oil

- Fired Steam Boilers 0.1 6497.0 447.3 83.7 250.1 365.8 507.4 1118.2

7.3.1.2 Determination of Equipment Sizing

To support calculation of space heating energy use, DOE had to establish a methodology for deriving the boiler capacities of each of the sampled buildings. The Department calculated the input capacity for the existing boiler of each housing/building unit based on information derived from the RECS and CBECs data. The sizing approach determines the input capacity of the sampled household/building by accounting for building characteristics that include the building square footage, building vintage, foundation type, shell characteristics, number of floors, outdoor design temperature and two factors that correct the building heating loss.

These characteristics are needed to estimate the building total heat loss. DOE utilized information from several boiler manufacturers and distributors to develop a methodology to derive the heat loss per square foot. Using the total heat loss value, DOE identified boiler models

wi th an output capacity capable of meeting the calculated heat loss of the home. Appendix 7

- B presents the variables used as well as further information about the building characteristics and heat loss values used for the sizing of boiler equipment.

Q in = AdjustedHeatLoss

AFUE baseline Eq. 7.3

. 6

Where:

AdjustedHeatLoss = estimated building heat loss adjusted for building characteristics (kBtu/ h ),

AFUE baseline = AFUE of the baseline boiler for each product class, for example, 82 percent AFUE for gas

- fired hot water boilers (see appen dix 7

- B).

7.3.2 Water Heating Energy Consumption

Boilers are often used to provide hot water in addition to space heating. The most

common means of doing so are through an indirect water heater, tankless coil, or as an integrated part of the boiler.7

- 11 RECS 2009 and CBECS 2003 do not provide any informa tion about when a boiler is used to provide hot water. DOE assumed that 50 percent of the installations in buildings reported in RECS or CBECS to use the same fuel for both space and water heating also use boilers for water heating , excep t when RECS repor ts the use of tankless water heating in which case DOE assumed that 100 percent would be serviced by a boiler. q

To calculate the water heating energy use, DOE calculated the boiler fuel use for water heating for each efficiency level based on the followin g equation:

FuelUse WH = WHL × ( AFUE

− Adj

_ Factor WH ) Eq. 7.3

. 7

Where:

WHL = water heating energy use based on RECS 2009 or CBECS 2003

, AFUE = AFUE of the selected efficiency level, and Adj_Factor WH = adjustment factor to take into account difference between AFUE and recovery efficiency for water heating (assumed to be

- 2%).

DOE used the following equation to calculate the water heating load (WHL):

WHL = � Q YR

, HW × ( AFU E
ex − Adj

_ Factor WH ) �

Eq. 7.3

. 8

Where:

Q YR,HW = annual fuel consumption for water heating based on RECS 2009 or CBECS 2003 (kBtu/yr),

AFUE

ex = AFUE of the existing boiler (see appendix 7

- B ), and Adj_Factor WH = as defined previously.

7.3.3 Electricity Consumption

The Department calculated boiler electricity consumption for the circulating pump , the draft inducer, and the ignitor. r The circulating pump move s water through the house whenever

the boiler burner is on (adjusted for delay times between burner and pump operation). It also operates in the cooling season (summer) if the re is a call for water heating (only in instances

where the boiler also serves th e home’s or building’s water heating loads) . In the case of modulating condensing boilers, in order to accommodate for lower firing rates, the inducer will provide lower combustion airflow to regulate the excess air in the combustion process . DOE has

assum ed that modulating condensing boilers are equipped with inducer fans with PSC motors

and two

- stage controls

. Low

- firing operation corresponds to a firing input rate of 90% or less of

q DOE believes that almost all the RECS households that reported a tankless water heater together with a boiler actually are using the boiler to provid e water heating either as a tankless coil or other combination unit type.

r The DOE and ASHRAE test procedures do not count the electricity used by controls when the boiler is not firing.7

- 12 the full input capacity . The inducers are assumed to run at 7 0% airflow r ate w hen the modulating unit operates at low

- fire. DOE also took into account the electricity consumption of such auxiliary equipment as condensate pumps and heat tape, which are sometimes installed with higher efficiency equipment. For single

- stage boilers, t he Department calculated the electricity consumption as: s

ElecUse TOTAL = ( BOH SH + BOH WH ) × CompE + ElecUse Stby Eq. 7.3

. 9

Where:

BOH S H = as defined previously

, BOH WH = as defined previously

, CompE = power of multiple electrical components required during boiler operation

, ( kW ) (refer to the test procedure variables detailed in Appendix 7

- B)

, and

ElecUse Stby = energy consumption during standby (kW h ).

For the standby and off mode evaluation, t he Department calculated the standby electricity consumption as:

ElecUse Stby = StbyE × ( 8760

− BOH SS + BOH WH )

Eq. 7.3

. 10

Where:

BOH S H = as defined previously,

BOH WH = as defined previously, and StbyE = power consumption during standby (kW).

Table 7.3.5 summarizes the standby hour results

.

Table 7.3.5 Range of Standby Hou rs for Each Boiler Product Class, Hours

Product Class Min Max Average Percentiles

5% 25% 50% 75% 95%

Gas

- Fired Hot Water

Boilers 3584.3 8759.8 8267.0 7720.5 8145.1 8362.8 8480.9 8613.3

Gas

- Fired Steam Boilers 2992.7 8758.7 8313.4 7693.4 8219.5 8405.5 8504.1 8639.7

Oil

- Fired Hot Water

Boilers 4068.5 8759.9 8323.4 7766.6 8250.9 8389.8 8501.2 8648.4

Oil

- Fired Steam Boilers 4036.7 8759.9 8332.7 7691.4 8269.3 8408.4 8520.9 8679.7

Electric Hot Water

Boiler 916.1 8760.0 6518.8 4045.3 5719.5 6507.3 7906.0 8407.0

Electric Stem Boilers 916.1 8760.0 6518.8 4045.3 5719.5 6507.3 7906.0 8407.0

s For two

- stage and modulating equipment

, this formula includes parameters for the operation at full, modulating, and reduced load. See appendix 7

- B.7

- 13 Some higher efficiency installations require the use of auxiliary equipment such as condensate pumps and heat tape. The electricity consumption of this equipment is calculated by DOE and added to the total electricity consumption. If a household required a condensate pump, DOE assumed that it consumed 60 watts and operated at the same time as the burner. If a household required heat tape to prevent the condensate pipe from freezing , Details of how DOE determined whether a household required a condensate pump can be found in appendix 8

- D

.

Further details for calculating electricity consumption appear in appendix 7

- B

.

7.4 SUMMARY OF ENERGY USE RESULTS

This section presents the average annual energy use and the average energy savings for each considered energy efficiency level compared to the baseline energy efficiency for each

boiler product class. The results reflect energy use in both the residential and commercial samples. t The LCC and PBP analysis uses the results calculated for each sample building.

t Residential boilers used commercial applications account for 7 percent of the building sample. See Appendix 9

- B.7

- 14 Table 7.4.1 Average Annual Energy Consumption and Savings for Residential

Boilers

Design Option Annual Fuel Use Annual Electricity Consumption of Auxiliary

C omponents

Total Savings Total Savings

MMBtu/yr MMBtu/yr kWh/yr kWh/yr

Gas

- fired Hot Water Boiler

0 82% AFUE

- Baseline 88.7

- 202.8

-

1 83% AFUE

– Increased HX Area 87.6 1.1 209.3

- 6.6

2 84% AFUE

– Increased HX Area 86.6 2.1 206.4

- 3.6

3 85% AFUE

– Increased HX Area 85.5 3.1 221.5

- 18.7

4 90% AFUE

– Condensing Baseline 80.4 8.2 302.3

- 99.5

5 92% AFUE

– Increased HX Area 79.4 9.3 298.5

- 95.7

6 96% AFUE

– Max Tech 76.1 12.6 294.3

- 91.5

Gas

- fired Steam Boiler

0 80% AFUE

- Baseline 86.4

- 153.5

-

1 82% AFUE

– Increased HX Area 84.3 2.1 154.0

- 0.6

2 83% AFUE

– Max Tech 83.3 3.1 154.6

- 1.1

Oil

- fired Hot Water Boiler

0 84% AFUE

- Baseline 84.2

- 273.4

-

1 85% AFUE

– Increased HX Area 83.2 1.0 265.7 7.8

2 86% AFUE

– Increased HX Area 82.3 1.9 259.0 14.4

3 91% AFUE

– Max Tech 78.7 5.5 287.4

- 14.0

Oil

- fired Steam Boiler

0 82% AFUE

- Baseline 86.1

- 245.3

-

1 84% AFUE

– Increased HX Area 84.0 2.0 242.6 2.7

2 85% AFUE

– Increased HX Area 83.0 3.0 238.3 7.0

3 86% AFUE

– Max Tech 82.1 4.0 239.1 6.27

- 15 7.4.2 Standby Energy Consumption Results for Boilers

Table 7.4.2 shows the average annual standby energy use for boilers and the average energy savings for each energy efficiency level, compared to the baseline.

Table 7.4.2 Average Annual Standby Consumption and Savi ngs for Residential

Boilers

EL Design Option Annual Electricity Consu mption for Standby

Total Savings
kWh/yr kWh/yr

Gas

- fired Hot Water Boiler

0 Baseline 119.0

1 Linear PS, Toroidal Xfmr 107.1 11.9

2 Switch Mode PS 104.7 14.3

3 SMPS, Toroidal Xfmr 99.1 7.9

Gas

- fired Steam Boiler

0 Baseline 124.5

1 Linear PS, Toroidal Xfmr 112.1 12.5

2 Switch Mode PS 109.6 14.9

3 SMPS, Toroidal Xfmr 103.8 8.3

Oil

- fired Hot Water Boiler

0 Baseline 124.2

1 Linear PS, Toroidal Xfmr 111.8 12.4

2 Switch Mode PS 109.3 14.9

3 SMPS, Toroidal Xfmr 103.5 8.3

Oil

- fired Steam Boiler

0 Baseline 124.3

1 Linear PS, Toroidal Xfmr 111.8 12.4

2 Switch Mode PS 109.3 14.9

3 SMPS, Toroidal Xfmr 103.5 8.3

Electric Hot Water Boiler

0 Baseline 104.1

1 Linear PS, Toroidal Xfmr 91.1 13.0

2 Switch Mode PS 88.5 15.6

3 SMPS, Toroidal Xfmr 82.4 6.1

Electric Steam Boiler

0 Baseline 104.1

1 Linear PS, Toroidal Xfmr 91.1 13.0

2 Switch Mode PS 88.5 15.6

3 SMPS, Toroidal Xfmr 82.4 6.17

- 16 REFERENCES

1. U.S. Department of Energy: Energy Information Administration, Residential Energy Consumption Survey: 2009 RECS Survey Data, 2013. (Last accessed March, 2013.)

< http://www.eia.gov/consumpt ion/residential/data/2009/ >

2. U.S. Department of Energy: Energy Information Administration, Commercial Buildings Energy Consumption Survey, 2003. (Last accessed September, 2013.)

< http://www.eia.doe.gov/ emeu/cbecs/ >

3. Energy Information Administration, Annual Energy Outlook 2013 with Projections to

2040 , 2013. Washington, DC. < http://www.eia.gov/forecasts/aeo/pdf/0383(2013).pdf >

4. Nati onal Oceanic and Atmospheric Administration, NNDC Climate Data Online, (Last accessed March 15, 2013.) <www7.ncdc.noaa.gov/CDO/CDODivisionalSelect.jsp>