Page 108 - Zero Net Energy Case Study Homes-Volume 1

CASE STUDY NO. 5
COLONIAL HOUSE MULTI-FAMILY HOUSING
Building Envelope – Air-tightness
The Colonial House project construction is built to the high energy-efficiency standards of En- ergy Star for Homes v2.0 3 with complete HERS measures4 implemented. However, multifamily housing is not required by Energy Star or HERS certification to have air-tightness testing, nor are there guidelines offered by the California Energy Commission, because it is possible to have air leakage between adjacent units although the unit is well-sealed to the exterior. So, verifying airtightness with a Blower Door Test would not yield meaningful results. However, the construc- tion was required to undergo QII Inspection5 as part of the certification process, which makes it likely that an acceptable level of airtightness was achieved.
Heating, Ventilating and Cooling Systems
Because of the proximity to the ocean and its cooling breezes, no mechanical cooling is installed in any of the housing units. As a result, many of the occupants utilize portable room fans to aug- ment the natural ventilation and to provide a cooling assist on exceptionally warm days. The community rooms (laundry, manager’s office and meeting room), however, are supplied with air conditioning via a package heat pump unit.
With no mechanical cooling of the individual units, heating is simplified by providing in-wall elec- tric resistance heating, placed in the living room and bedrooms of each unit. Due to the Energy Star levels of insulation and inspection, the project was able to reduce initial cost by using elec- tric resistance heating, which is unusual in high performance housing but well-suited for this temperate climate. In the first year, only two apartments needed the electric resistance heating.
Domestic Hot Water
Every unit, including the community laundry room, has a dedicated electric heat pump water heater. An innovative idea at the time, these energy-efficient water heaters, when combined with the electric ranges, allowed the design of an all-electric, zero-carbon housing project.
Daylighting and Electric Lighting
Windows are concentrated in the living areas and bedrooms, while the kitchens are open to the living spaces, so the sense of all the units is that of a light-filled apartment. In addition, high ef- ficiency lamps are provided in all light fixtures.
Plug Load and Equipment
All appliances are Energy Star, including the washers and dryers located in the community laun- dry facilities. Cooking is done by electric ranges (not induction ranges)..
3 Energy Star Certified Homes Program The ENERGY STAR Certified Homes program helps homebuyers easily identify homes that are significantly more energy efficient than standard con- struction in the marketplace. For certification requirements, see: https://www.energystar.gov/in- dex.cfm?c=bldrs_lenders_raters.homes_guidelns.
4 Home Energy Rating System (HERS) is a series of energy code verification procedures that are used to confirm that certain building features are meeting their full performance during construc- tion. See the discussion in the Introduction to this book for more details about the HERS Rating System in California.
5 QII Inspection is “Quality Installed Insulation Inspection”, which means it was carefully inspected throughout construction for proper air tightness sealing (all cracks, penetrations, wall junctures) and careful insulation installation. There is no testing associated with this inspection, however.
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Zero Net Energy Case Study Homes: Volume 1