High Performing Buildings - Summer 2012 - (Page 62)

three-way valves bypassing coils to keep the loop maintained at a temperature that will not delay the response of calls for heating or cooling. With heat pumps, as long as the loop is maintained between 45°F–90˚F, there is no reason to move water when there are no units actively calling for it because they can operate with much wider loop BuiLding EnvELopE Roof Type Simulated slate with structural insulated panel (SIP) roof system Overall R-value 40 Re ectivity SRI 25 Walls Type Load-bearing brick with offset metal studs, closed-cell foam insulation, and blown-in wood ber cellulose insulation Overall R-value 24 (continuous) Glazing Percentage 10.9% Basement/Foundation Basement Wall Insulation R-value 10 Basement Floor R-value 10 Windows U-value 0.30 Solar Heat Gain Coef cient (SHGC) 0.2 Visual Transmittance 0.46 Location Latitude 41.1306° N Orientation East-west temperatures. Based on the first year of operations, the main pumps are turned off approximately 20% of the time with no call for water flow. The replace in the lobby uses bricks reclaimed from the demolished interior load-bearing walls. Standby Mode To save additional energy, the heat pumps go into standby mode when the lighting system occupancy sensors determine that a space is unoccupied for at least 20 minutes. Once this occurs, the unit’s supply fan shuts down, and the space temperature setpoints change to allow for a wider dead band in an effort to prevent the compressor from running to maintain an empty room. The typical dead band used in the building is ±2˚F. However, when in standby mode, this is changed to ±4˚F. The gray area in Figure 2 indicates when the occupancy sensor detects people in the space and normal sequences are followed. The black regions indicate time periods when a 20-minute interval of no occupancy was determined, and the heat pump went into standby mode. The heat pump supply fan is shut off because a dedicated outside air supply system provides the required minimum airflow separate from the heat pumps to each space. The room in Figure 2 is a conference room that is used sparingly Summer 2012 © Viridian Architectural Design, Fort Wayne, Ind. during most work days. The heat pump spends about 90% of the time in standby mode. When the space is occupied for a short period in the morning, the space temperature is pulled down. However, once in standby mode the space temperature rises to approximately 78˚F while the cooling set point is elevated. Later in the afternoon, the space is again occupied, and the space temperature recovers within a couple of minutes and remains near setpoint until the space is again vacated. The outside air ventilation system for this building consists of a fixedplate energy recovery unit that uses building exhaust to precondition the incoming outside air, which is delivered directly to each zone. Having limited equipment room space, this unit is only sized for the coderequired outside air volume and not a full outside air economizer volume due to limitations on duct paths. To minimize thermal bridging through the exterior walls and to help seal the “leaky” brick shell, 1 in. to 2 in. of spray foam insulation was used on the inside face of all exterior walls. Then, 3 5/8 in. metal studs were offset 1.5 in. off the face of the exterior brick. 62 HIGH PERFORMING BUILDINGS The building is being used as a lab for engineering students. Data from the geothermal systems is given to students as a way to study a real-world application of an energy-ef cient technology. © Snap This Photography, Fort Wayne, Ind.

Table of Contents for the Digital Edition of High Performing Buildings - Summer 2012

High Performing Buildings - Summer 2012
Commentary
Contents
High Tech High Chula Vista
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La Reunion’s ENERPOS
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High Performing Buildings - Summer 2012

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