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TCAAP Energy Integration Resiliency Framework Energy Efficiency Strategies 65 4.3.2. Building orientation and passive solar The TCAAP Policy White Paper included the recommendations for the TCAAP subdivision review process to assess the energy implications of street and building orientation on solar heat gain and loss. Beyond the building envelope, street orientation, lot and building orientation, and building massing, all impact the thermal loads of homes and commercial buildings. By jointly considering these variables prior to the subdivision process, planners and developers have the opportunity to make tradeoff decisions while still producing efficient results. Site orientation is potentially a no-cost way to reduce building energy loads and improve daylighting when considered in site planning. In line with solar oriented design, homes should be designed and sited so that the longest sides of a house face south and southern faces have the greatest window area.14 This general window orientation is a proven strategy to reduce a home’s heating energy by approximately 4% and cooling costs by 2%, without affecting any other parts of the design. Figure 11 shows the energy savings achieved from southern window orientation, assuming that the largest exterior walls are facing north and south, but without optimizing any other window characteristics or the window to wall ratio on each side. Alone, window orientation results in moderate energy savings, but when paired with improved window insulation, higher solar heat gain coefficients, and optimum window to wall ratios, the heating energy savings will be 20% to 30%.15 Proper building and window orientation magnify the impact of the remaining window decision. When aligned, homes with a well-insulated double or triple pane windows 14http://www.energy.ca.gov/title24/2013standards/prerulemaking/documents/current/Reports/Residential/Water_Heating/2013_CASE _R_Solar_Ready_Solar_Oriented_Developments_Sept_2011.pdf 15 http://www.efficientwindows.org/downloads/ColdDesignGuide.pdf Recommendation: The process for solar oriented development should be described in residential and commercial building RFPs and should be integrated as evaluation criteria for development proposals. It should be evaluated based on lowest total energy load of the homes or buildings to be sited under one proposal and should consider street orientation, building orientation, and passive solar building envelope design elements. As part of the platting process, the County could plat the land and maximize building orientation prior to sale to developers.