High Performing Buildings - Winter 2011 - (Page 55)

operate only when their respective heat pump compressor is on. Purging air from the piping of distributive pumping systems is much more difficult than doing so in a central pump system. The piping system in a distributive pumping system should be designed to facilitate air venting. A single rooftop unit serves as a dedicated outdoor air unit (DOAS). The unit is equipped with a supply fan, exhaust fan, heat recovery wheel and variable frequency drives (VFDs) for each fan. A demand control ventilation system supplements the DOAS to modulate the outside air introduced into the building in response to the actual space air quality. A system that provides central testing of CO2, Below, left Heat pump rooms are located on the first and second floors of the building. Individual water pumps are sized for each heat pump and recirculate water through the geothermal loop without the aid of central pumps. Water pumps only operate when their respective heat pump compressor is on, saving energy. Below, right Although this section of the building resembles two separate federal style townhouses, the second floor is actually a single open-office space. The unfinished first-floor area may be used for future expansion, or the firm may lease the space. total volatile organic compounds (TVOC) and dew point was chosen in lieu of room CO2 sensors to increase reliability. A 2007 Lawrence Berkeley National Laboratory study found that only 27% of room sensors were accurate within a ±20% range. Central testing allows the use of lab quality sensors without being cost prohibitive. eight air sensing ports return air to a central sensing panel via a 0.25 in. pneumatic tube system to measure actual air conditions in each of eight control zones. The sensing panel compares indoor CO2 to the outdoor level. Then, through an interface to the direct digital control (DDC) system, the system opens or closes outside air variable air volume (VAV) boxes to maintain a 700 ppm differential for each zone. When meetings occur in the large conference room, the room CO2 level immediately increases. The respective outside air VAV box opens as necessary to maintain the CO2 setpoint. During normal operating hours, CO2 levels are maintained well below the 700 ppm setpoint. Measurement and testing Another goal is to use the building to measure and test green systems. As discussed previously, measuring the energy consumption independently for each building system (hVAC, lighting, plug loads and PV) allows for the comparison of actual energy data with the predicted energy model. each month when utility invoices are received, energy usage from the building’s digital electric metering system is read to compare data, trend results and ensure performance. in addition to the electricity consumption, the geothermal field and iCF wall system are monitored. Three vertical pipe bores are backfilled in three different ways; one is backfilled with rock shavings, another with rock and the last with a high performance grout. each vertical bore is equipped with temperature sensors in the supply and return pipes. The temperature of the water returning to the building from each bore was analyzed. The data indicates that the bore with the rock shaving backfill lags behind the performance of the others by several degrees. Winter 2011 HigH Performing Buildings 55 Kenneth l. seibert dean lavenson

Table of Contents for the Digital Edition of High Performing Buildings - Winter 2011

High Performing Buildings - Winter 2011
Commentary
Contents
Portland State's Shattuck Hall
Oberlin College's Adam Joseph Lewis Center
Dell Children's Medical Center
CMTA Office Building
EPA Region 8 Headquarters
Honda's East Liberty, Marysville Auto Plants
Advertisers Index

High Performing Buildings - Winter 2011