The New 2001 Residential Washington State Energy Code
A new Washington State Energy Code, titled the 2001 Washington State Energy
Code, came into effect on July 1, 2002. Significant changes to the
residential portion of the code have occurred.
The key changes to the residential code are highlighted in the following
list:
1) The new code is fuel blind.
For the most part, the new code does not distinguish between gas and electric heat sources, as earlier versions did. The parallel compliance paths for electric space heating and “other fuels” space heating (including gas, oil, heat pumps, etc.) have all but been eliminated. There is still a minor difference on the calculated path with R-19 walls for gas heat, and R-21 walls for electric heat. Otherwise, the building envelope requirements are now the same for all space heating types. The parallel compliance paths for Climate Zone 1 (Western Washington) and Climate Zone 2 (Eastern Washington) remain in the new code.
2) An unlimited glazing prescriptive path is available for single family (R-3 occupancy) only.
A new unlimited glazing prescriptive path calls for glazing with 0.40 U-value, R-38 attics, R-30 floors, R-21 walls, and 0.20 U-value opaque doors. For information on the glazing specifications needed to meet a U-value of 0.40, see “How to Meet the 0.40 U-value Requirement for Vertical Glazing.” For information on the specifications needed to meet a door U-value of 0.20, see “How to Meet the 0.20 U-value Requirement for Doors.”
3) Compliance for multifamily and some residential buildings will be more difficult.
The new prescriptive table for Climate Zone 1, covering all space heating types, includes only three compliance options. There is one compliance path at 12 % glazing (of heated floor area), one path at 15% glazing, and a third path of unlimited glazing which is only available for single family (R-3 occupancy). Under the new Component Performance approach, (also known as calculated method or Target UA approach), there will be only one compliance path for all space heating types, (with the exception mentioned above of R-19 walls for gas, and R-21 walls for electric). The target building for the new component performance approach is essentially the electric path target building used under the previous version of the code. Thus for electrically heated buildings the component performance approach will remain largely unchanged, whereas for buildings heated by “other fuels” the new component performance approach target building will result in a much more stringent compliance path. Multifamily buildings are currently ineligible for the unlimited glazing path. This issue is being contested and it appears possible that high-rise multifamily may soon be exempted from the new code altogether. See our “Update on Multifamily Construction and the New 2001 WSEC,” for more information and updates as they become available.
The new code encourages you to stay within the requirements of the unlimited glazing prescriptive path for single family homes whenever possible. The calculated path will only be used for multifamily buildings or, as a last resort, for single family buildings when the unlimited prescriptive path cannot be met. For example, if a single family home design includes some 2x4 walls, or a window specification that cannot meet 0.40, the building might have to comply with the component performance approach. It will be difficult to do this successfully, unless the building has a low glazing percentage.
4) The WATTSUN program is no longer a certified code compliance tool.
Systems analysis evaluations are now more difficult to execute because the popular WATTSUN software program is no longer an acceptable method to demonstrate code compliance. There are other certified programs available to perform system analysis evaluations, including SUNDAY a program written at Ecotope. Unfortunately, SUNDAY was written long before the days of user-friendly interface design. It is therefore difficult for new users to learn and use. Ecotope will not be providing free technical support, because we do not have the staff and resources to do so. For these reasons, we recommend that if you need a systems analysis evaluation using SUNDAY, hire us to do it – it will save you time and money.
Can Your Design Really Include Unlimited Glazing?
Many architects for custom home projects are used to being faced with the
prospect of removing glazing or significantly increasing insulation values
in order to meet code requirements. Under the new code, provided that
all the other components of the building are on the prescriptive path, there
is no limit on the glazing area allowed for a single family building.
This fact has tremendous implications for your design freedom. However,
this design freedom should be used thoughtfully. Up to this point, the energy
code compliance standards for a project have served to ensure a standard
level of performance for all new buildings. If a building design met
the requirements of the Washington State Energy Code, one would feel assured
that the building could be conditioned to provide a reasonable level of comfort
for the occupants, and that the heating and cooling energy bills would be
reasonable. Under the new unlimited glazing prescriptive path, the responsibility
to consider the energy performance and occupant comfort goals of a project
is put back into the designers’ hands. The potential now exists for
you to design a building which meets aesthetic goals, while the mechanical
systems are unable to satisfy thermal comfort standards, or are exorbitantly
expensive to operate. Considering that most regional energy prices
have approximately doubled in the last year, this is not an insignificant
danger. Conversely, the potential exists for you to design a building
which meets aesthetic goals and is designed to avoid compromising the energy
performance.
How Ecotope Can Continue to Help You
Because the new energy code can get you into trouble with performance issues,
it is now doubly important to pay attention to energy performance in your
building designs. Ecotope will continue to offer you consulting on
building energy performance and HVAC system design services, and we now offer
LEEDTM documentation services. We can provide you with the technical
support required to create a building design which integrates the envelope
configuration, insulation, and the space conditioning equipment to result
in an excellent building. For those projects which cannot use the unlimited
glazing path, or are otherwise complex, we will continue to offer code compliance
support. As you probably know from experience, evaluation of energy
conservation measures is best started early on in the building design process.
Consider enlisting Ecotope’s services during the design development phase
of your next project, so that we can help you evaluate the thermal comfort
and energy performance of the building throughout the design process.
See the SERVICES section of our website and follow the links to our mechanical and architectural design/consulting
services and our sustainable design services, for more information on the
services we can offer you.
More Information
More information on the changes to the Washington State Energy Code and the
Seattle Energy Code is available in the June 2002, and January 2002 volumes
of the on-line newsletter of the Seattle DCLU at: http://www.cityofseattle.net/dclu/publications/info/Default.asp.
The full text of the 2001 Washington State Energy Code may be downloaded
in pdf format from the Washington State Building Code Council’s website:
http://www.sbcc.wa.gov/pages/WSEC2001.htm.