LEED BD+C: Homes v3 - LEED 2008
448 Green Home
LEED Platinum 2011
Opportunities for sustainability and efficiency were identified at the earliest stages of design. Simple and passive approaches were favored over active and complex.
The Project is a 2,634 sf2 single-family home on a 30ft X 90ft lot in a dense Southern California coastal community. The 448 building was conceived as a case study to challenge the perception that sustainability invariably carries a series of unpleasant tradeoffs and penalties. The project aimed to offer a substantially improved product with virtually no negative impact to cost, convenience, aesthetics or comfort. Participation in a stringent third party certification program provided verification.
Opportunities for sustainability and efficiency were identified at the earliest stages of design. Simple and passive approaches were favored over active and complex. Water efficiency and runoff reduction were also identified as critical considerations for the Southern California coastal environment. Although the moderate coastal climate offered several benefits, relatively small parcels and tight adjacencies posed challenges to achieving adequate solar and ventilation access, logistics, privacy and usable outdoor space. These issues were primarily addressed through an open, flexible and efficient floor plan and building envelope. Operable partitions and extensive fenestration enhanced functionality, and an "annex" outdoor space provided ample daylight and ventilation. 3-D modeling guided active and passive strategies for solar, ventilation, light transmittance, privacy and thermal performance while all fixtures, equipment and systems were selected for their inherent efficiency. With the overall building and its various systems within targeted efficiency ranges, active energy systems were appropriately downsized.
The strategy for reducing embodied energy was similar. The overall design prioritized efficient use of materials, labor, and resources. Materials with high levels of embodied energy were minimized and locally sourced materials composed of high-recycled content and/or rapidly renewable materials were prioritized. Construction-generated waste was significantly reduced and a number of durability strategies were incorporated.
Initial targets were LEED® Gold certification and energy efficiency 30% better than state mandates. Ultimately, the project achieved a computer-modeled efficiency that is 38.75% better than code and actual, annualized performance is 45% better. A 4.1 kW photovoltaic array provides a net surplus, flat plate collectors provide hot water demand and runoff is near zero. LEED® Platinum certification was awarded in May 2011 and the budget and schedule were well under community averages.