High Performing Buildings - Spring 2008 - (Page 22) air, lowering the energy requirements to condition the ventilation air. The CO2 based demand-controlled ventilation requirements determine the ERV fan speed. Energy Analysis Energy analysis for the visitor center is based on the USGBC LEED® Energy Modeling Protocol (EMP) illustrated in the LEED for New Construction (NC) Version 2.1 Reference Guide. The basis for this comparison is the ANSI/ASHRAE/ IESNA Standard 90.1-1999, Energy Standard for Buildings Except Low-Rise Residential Buildings, Energy Cost Budget (ECB) method. Exceptions and clarifications are noted below. The composting toilet system requires continuous ventilation at 75 cfm per fixture. Because energy recovery from this airflow is not possible, restroom air conditioning is not provided and heat is supplied by electrical resistance heaters. Exhaust fans located at each compost bin in • With electric lights off or dimmed during daylight hours, 41% of the total building area uses daylight as the dominant light source. a 12 in. deep intensive vegetated green roof, and 63% are high reflectivity/high emissivity metal roofing, reducing the heat island effect. The earth-sheltered construction and green roofs act as a heat sink and moderate the temperature differentials between the building interior and exterior air. High insulation values of R-40 for the roofs and R-19 for the walls further reduces heating and cooling loads. and cultural value. The building’s ventilation is 100% mechanically controlled because of the importance of filtration and keeping the temperature and humidity within a narrow range. An energy recovery ventilator (ERV), consisting of a supply fan, exhaust fan and rotary enthalpy heat wheel, reclaims some of the sensible and latent heat from the building’s exhaust airflow. The ERV uses this heat to pretreat the incoming outside Active Design Strategies A 10.5 kW rated capacity photovoltaic solar array on the south-facing portions of the building’s roofs generates approximately 20% or 14,124 kWh per year of the building’s electricity. Figure 1 provides a breakdown of the projected photovoltaic production. Automatic lighting controls regulate artificial lighting with photocells and timers. The building’s HVAC system consists of multiple zones using high efficiency HVAC systems with multiple speed fans, two-stage compressors and ratings of 15 SEER and 12 EER. The building contains sensitive archives of significant historical 22 HIGH PERFORMING BUILDINGS Vegetated green roofs act as a heat sink and moderate the temperature differentials between the building interior and exterior air. Spring 2008
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