The King County Housing Authority’s (KCHA) new office headquarters was a complete interior renovation of a former big box retail store that brings together previously separated departments and promotes an integrated agency culture. The 36,000 sf remodeled space contains all major functions of a typical modern office. The project goals were to create an affordable energy efficient “Net Zero Energy Ready” building. The design team delivered on this goal in within an aggressive schedule and tight budget. The project was completed on time for a total cost of $95/sf using careful design and readily available off- the-shelf technology.
Energy efficiency features include high efficiency crossflow Energy Recovery Ventilation (ERV) with EC motors, a Variable Capacity Heat Pump (VCHP) system with 50-zones, dimming lighting controls for corridors and perimeter day-lit lighting zones, low lighting power design (0.7 W/sf), and occupancy controls on all lights in rooms with doors. Existing glazing was replaced with high performance low-e glazing with U-Factor 20% better than ASHRAE 90.1-2007 requirements. The glazing SHGC of 0.18 is less than half the maximum allowed by ASHRAE 90.1-2007 and was specifically selected to reduce cooling loads of the large West-facing façade. Triple glazed translucent skylights were added to provide daylighting into interior corridors and office zones without significantly increasing heating and cooling requirements.
Low flow plumbing fixtures result in 30% less potable water use per year than a code built building. The project is achieving an annual Energy Use Index (EUI) of 27 kBtu/sf-yr based on the first nine months of full occupancy. This is 1/3 the energy use of the KCHA’s other primary office building across the street and 70% less than the Commercial Building Energy Consumption Survey (CBECS) 2003 national average for office buildings of 93 kBtu/sf-yr.
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