Washington Administrative Code › Title 51 - Enterprise Services, Department of (Building Code Council) › Chapter 51-11C - State Building Code adoption and amendment of the 2021 edition of the International Energy Conservation Code, Commercial › Section 51-11C-40314 - Section C403.1.4-HVAC heating equipment

Current through Register Vol. 24-14, July 15, 2024
C403.1.4
Use of
			 electric resistance and fossil fuel-fired HVAC heating equipment.
HVAC
			 heating energy shall not be provided by electric resistance or fossil fuel
			 combustion appliances. For the purposes of this section, electric resistance
			 HVAC heating appliances include, but are not limited to, electric baseboard,
			 electric resistance fan coil and VAV electric resistance terminal reheat units
			 and electric resistance boilers. For the purposes of this section, fossil fuel
			 combustion HVAC heating appliances include, but are not limited to, appliances
			 burning natural gas, heating oil, propane, or other fossil fuels.
EXCEPTIONS:
1.
Low heating capacity.
Buildings or
						  areas of buildings, other than
dwelling units
or sleeping
						  units, that meet the interior temperature requirements of Chapter 12 of the
International Building Code
with a total installed HVAC
						  heating capacity no greater than 8.5 Btu/h (2.5 watts) per square foot of
conditioned space
are permitted to be heated using electric
						  resistance appliances.
2.
Dwelling and sleeping units.
Dwelling
						  or sleeping units are permitted to be heated using electric resistance
						  appliances as long as the installed HVAC heating capacity in any separate space
						  is not greater than:
2.1. Seven hundred fifty (750) watts in Climate Zone 4,
						  and 1000 watts in Climate Zone 5 in each habitable space with
						  fenestration.
2.2. One thousand (1,000) watts in Climate Zone 4, and
						  1300 watts in Climate Zone 5 for each habitable space that has two primary
						  walls facing different cardinal directions, each with exterior fenestration.
						  Bay windows and other minor offsets are not considered primary walls.
2.3. Two hundred fifty (250) watts in spaces adjoining
						  the
building thermal envelope
but without fenestration.
For the purposes of this on, habitable space is as
						  defined in the International Building Code. For buildings in locations with
						  exterior design conditions below 4°F (-16°C), an additional 250 watts
						  above that allowed for Climate Zone 5 is permitted in each space with
						  fenestration.
3.
Small buildings.
Buildings with less
						  than 2,500 square feet (232 m2) of
conditioned floor area
are permitted to be heated using
						  electric resistance appliances.
4.
Defrost.
Heat pumps are permitted to
						  utilize electric resistance heating when a heat pump defrost cycle is required
						  and is in operation.
5.
Air-to-air heat pumps.
Buildings are
						  permitted to utilize electric resistance supplemental heating for air-to-air
						  heat pumps that meet all of the following conditions:
5.1. Internal electric resistance heaters have controls
						  that prevent supplemental heater operation when the heating load can be met by
						  the heat pump alone during both steady-state operation and setback
						  recovery.
5.2. The heat pump controls are configured to use the
						  compressor as the first stage of heating down to an outdoor air temperature of
						  17°F (-8°C) or lower except when in defrost.
EXCEPTIONS TO 5.2:
1. Packaged terminal heat pumps (PTHPs) that comply
						  with the minimum heating efficiency requirements in Table C403.3.2(4) are
						  exempt from heating pump controls capable of operating the compressor as the
						  first stage of heating down to an outdoor air temperature of 17°F
						  (-8°C) or lower.
2. Heat pumps whose minimum efficiency is regulated by
						  NAECA and whose ratings meet the requirements shown in Table C403.3.2(2) and
						  include all usage of internal electric resistance heating are exempt from heat
						  pump controls capable of operating the compressor as the first state of heating
						  down to an outdoor air temperature of 17°F (-8°C) or lower.
5.3 The heat pump complies with one of the following:
5.3.1. Controlled by a digital or electronic thermostat
						  designed for heat pump use that energizes the supplemental heat only when the
						  heat pump has insufficient capacity to maintain set point or to warm up the
						  space at a sufficient rate.
5.3.2. Controlled by a multistage space thermostat and
						  an outdoor air thermostat wired to energize supplemental heat only on the last
						  stage of the space thermostat and when outdoor air temperature is less than
						  32°F (0°C) except when in defrost.
5.3.3. The minimum efficiency of the heat pump is
						  regulated by NAECA, its rating meets the requirements shown in Table
						  C403.3.2(2), and its rating includes all usage of internal electric resistance
						  heating.
5.4. The heat pump rated heating capacity is sized to
						  meet the heating load at an outdoor air temperature of 32°F (0°C) or
						  lower and has a rated heating capacity at 47°F (8°C) no less than 2
						  times greater than supplemental heating capacity in Climate Zone 4 and no less
						  than the supplemental heating capacity in Climate Zone 5, or utilizes the
						  smallest available factory-available internal electric resistance
						  heater.
6.
Air-to-water heat pumps.
Buildings are
						  permitted to utilize electric resistance (for Climate Zone 4 or 5) or fossil
						  fuel-fired (for Climate Zone 5) auxiliary heating to supplement heat pump
						  heating for hydronic heating systems that meet all of the following
						  conditions:
6.1. Controls for the auxiliary heating sources are
						  configured to lock out the supplemental heat when the outside air temperature
						  is above 36°F (2°C), unless the hot water supply temperature setpoint
						  to the building heat coils cannot be maintained for 20 minutes.
6.2. The heat pump controls are configured to use the
						  compressor as the first stage of heating down to the lowest exterior design
						  temperature for which the equipment is rated except during startup or defrost
						  operation.
6.3. The heat pump rated heating capacity at 47°F
						  (8°C) is no less than 75 percent of the design heating load at 29°F
						  (-2°C).
7.
Ground source heat pumps.
Buildings are
						  permitted to utilize electric resistance supplemental heating for heat pump
						  heating for hydronic heating systems with ground source heat pump equipment
						  that meets all of the following conditions:
7.1. Controls for the auxiliary heating sources are
						  configured to lock out the supplemental heat when the equipment source-side
						  entering water temperature is above 42°F (6°C) the hot water supply
						  temperature setpoint to the building heat coils cannot be maintained for 20
						  minutes.
7.2. The heat pump controls are configured to use the
						  compressor as the first stage of heating.
7.3. The ground source heat exchanger shall be sized so
						  that the heat pump annual heating output is no less than 70 percent of the
						  total annual heating output in the final year of a 30-year simulation using
						  IGSHPA listed simulation software.
8.
Small systems.
Buildings in which
						  electric resistance or fossil fuel appliances, including decorative appliances,
						  either provide less than 5 percent of the total building HVAC system heating
						  capacity or serve less than 5 percent of the
conditioned floor
						  area
.
9.
Specific conditions.
Portions of
						  buildings that require fossil fuel or electric resistance space heating for
						  specific conditions
approved
by the
code
						  official
for research, health care, process or other specific needs
						  that cannot practicably be served by heat pump or other space heating systems.
						  This does not constitute a blanket exception for any occupancy type.
10.
Kitchen make-up air.
Make-up air for
						  commercial kitchen exhaust systems required to be tempered by Section 508.1.1
						  of the
International Mechanical Code
is permitted to be heated
						  by using fossil fuel in Climate Zone 5 or electric resistance in Climate Zone 4
						  or 5.
11.
District energy.
Steam or hot water
						  district energy systems that utilize fossil fuels as their primary source of
						  heat energy, that serve multiple buildings, and that were already in existence
						  prior to the effective date of this code, including more energy-efficient
						  upgrades to such existing systems, are permitted to serve as the primary
						  heating energy source.
12.
Heat tape.
Heat tape is permitted
						  where it protects water-filled equipment and piping located outside of the
building thermal envelope,
provided that it is configured and
						  controlled to be automatically turned off when the outside air temperature is
						  above 40°F (4°C).
13.
Temporary systems.
Temporary electric
						  resistance heating systems are permitted where serving future tenant spaces
						  that are unfinished and unoccupied, provided that the heating equipment is
						  sized and controlled to achieve interior space temperatures no higher than
						  40°F (4°C).
14.
Pasteurization.
Electric resistance
						  heat controls are permitted to reset the supply water temperature of hydronic
						  heating systems that serve service water heating heat exchangers during
						  pasteurization cycles of the service hot water storage volume. The hydronic
						  heating system supply water temperature shall be configured to be 145°F
						  (63°C) or lower during the pasteurization cycle.
15.
Freeze protection.
Heating systems
						  sized for spaces with indoor design conditions of 45°F (7°C) and
						  intended for freeze protection are permitted to use electric resistance. The
						  building envelope of any such space shall be insulated in compliance with
						  Section C402.1.
16.
DOAS ERV auxiliary heat.
Dedicated
						  outdoor air systems with energy recovery ventilation are permitted to utilize
						  fossil fuel for Climate Zone 5 or electric resistance in Climate Zone 4 or 5
						  for auxiliary heating to preheat outdoor air for defrost or as auxiliary
						  supplemental heat to temper supply air to 55°F (13°C) or lower for
						  buildings or portions of buildings that do not have hydronic heating
						  systems.
17.
Low-carbon district energy systems.
Low-carbon district energy systems that meet the definitions of
low-carbon district energy exchange system or low-carbon district
						  heating and cooling or heating only systems.
18.
Essential facilities.
Groups I-2 and
						  I-3 occupancies that by regulation are required to have in place redundant
						  emergency backup systems.