ASHRAE Journal - May 2011 - 84

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range of 40% to 60% during this time period. The humidity spikes observed in the master bedroom area each day are from shower moisture. The humidity sensor is located approximately 2 m (6.5 ft) from the bathroom door, which is generally left open during showers. The open bathroom design has no shower enclosure or shower curtains (one can “tour” these areas with the 3-D model located on our website: http://newellinstruments.com). The ventilation system has proven very effective at purging moisture out of the bathroom, and at least since last November, no residual moisture has been observed in the Figure 3: View of utility chase (attic) where the heat pump, fresh air ventilation system master bathroom a few hours after use. and the heat pump water heater are located. During the vacancy at the end of January, a drop in interior humidity was recorded. Supply Air Duct to Master The basis for choosing interior ambiBedroom and Living Room ent conditions is based on whether Deb Exhaust Air to Outside Newell, Ty’s spouse and Ben’s mother, Return Air From Kitchen, Laundry is comfortable. Her vote is the only vote And Bathrooms that counts for comfort. During the winFresh Air ter, typical dress and metabolic activity Inlet Duct With are in the 1 to 2 clo and 1 to 2 met range Filter Box (see Chapter 9 of ASHRAE Handbook— Supply Air to Three Bedrooms Fundamentals; 1 to 2 clo represents long sleeve shirts, sweater, pants while 1 to 2 met represents relaxed and sitting to a cooking level of activities). As described in previous columns, the level of wall and roof insulation in Equinox and Figure 4: View of ventilation ductwork showing the fresh air filter box, exhaust air modest window area results in radiant duct, ventilation supply air to living room and bedrooms, and return air from kitchen, surfaces being very close to ambient air laundry and bathrooms. temperature. Air velocities throughout the house are undetectable, and humidity is generally in the compounds from an herbal tea good or bad? In our case, we are in40% to 60% range. terested in understanding how periods of human activity correlate Healthy indoor climates should keep odors minimized and with CO2 levels and VOC (odor) levels to implement a demand carbon dioxide maintained at reasonable levels as specified by controlled ventilation algorithm. Although very unscientific, we ASHRAE Standard 62.2 for residential ventilation. Figure 7 regularly ask visitors whether they are able to detect any odors, presents data from a carbon dioxide (CO2) sensor and a volatile and to date the consensus is that there are no odors. We should also organic compound (VOC) sensor we have located in the main note that Deb Newell is a prolific cook whose range of cooking living room of Equinox House. The VOC sensor saturates above activities generate an unbelievable amount of wonderful odors. 2,000 ppm and has a base level of approximately 390 ppm, The odors are no longer detectable the following day by visitors which represents a nominal outdoor air background level of (including some char producing cooking adventures). VOCs. The “ppm” unit used for the VOC sensor are scaled to Figure 8 presents transient data over an 11-hour period just represent the amount of CO2 that would be associated with the after Deb and Ty left for the ASHRAE conference (6 p.m., Jan. VOCs produced from a human rather than being actual VOC 28, 2011). The house was shut down, the fresh air ventilation parts per million. Other VOC producing events, such as from dampers were placed in a closed position, and the house was able cooking, candles, perfumes, cleaning chemicals, flooring ma- to coast for three days. The data in Figure 8 spans the nighttime terials, and building materials add to the VOC level, causing it when the impact of solar radiation was absent. The logarithmic to exceed the actual CO2 level from human respiration. variation of the temperature, humidity ratio, CO2 and VOC VOCs are quite interesting as they represent a family of com- sensors are shown in Figure 8, in a manner discussed in our pounds whose health effects are difficult to define. Are VOCs February 2011 column on thermal mass. The time constants generated from cooking good or bad for you? Are the aromatic of the four quantities, shown in Figure 8, vary from each other
84 ASHRAE Journal ashrae.org May 2011

ASHRAE Journal - May 2011

Table of Contents for the Digital Edition of ASHRAE Journal - May 2011