Title: Coquille Indian Reservation: Testing and Monitoring
Date: 13-14 October 1997
Location: Coos Bay, Oregon
Attending: Armin Rudd-Florida Solar Energy Center
Bob Abernethy-Florida Solar Energy Center
Allen Lee, Pacific Northwest Labs (14-Oct-97)
Dale Northcut-Univ. Of Oregon

Author: Armin Rudd

Purpose: Air tightness testing of structural insulated panel houses and a comparable wood frame house. Installation of energy use monitoring equipment in two houses.

Discussion:

On 13-Oct-97 five houses were tested by fan pressurization for building air tightness. Four of these houses were constructed, at least in part, with structural insulated panels (SIP's). One house was conventional 2x6 wood frame construction with a concrete slab foundation. Two of these houses, one SIP and the other wood frame, were also instrumented for energy use and indoor environment monitoring. A weather station was installed at the Coquille Housing Authority office. On 14-Oct-97 an additional SIP house was tested for building air tightness.

Table 1 lists the air tightness testing results and gives a short description of the construction. All of the houses tested had air exchange rates lower than average conventional construction with the exception of the Housing Authority office, which was the first SIP house built at the site. Conventional construction is often greater than 5.0 air changes at 50 Pascal pressure differential, barring special measures taken to achieve better building air tightness. None of these houses had a central air distribution system; these systems often lead to increased building air leakage. All of the houses were heated with Cadet zoned electric resistance heaters; usually having four or five zones- one for each bedroom, the hall, and the main living area.

All of the houses had air inlet vents at the top of at least one window in each room. In three of the houses, the multi-point (six measurements) fan pressurization air tightness test was conducted twice- once with window air inlet vents closed and once with the inlet vents open. The other houses were tested with the air inlet vents closed. As shown in Table 1, the change in effective leak area at 4 Pa, calculated from the multi-point test curve, did not change by more than 4 in² or 13% out of about 31 in². We usually found the inlet vents closed. Only three of the five homes were occupied, and, in only one of the three occupied homes did the occupants have any understanding of the vents. No dedicated fresh air ventilation system other than the window inlet vents had been installed. There had been no attempt to utilize the bathroom fan to provide controlled air exchange on either a continuous or periodic basis unless the bathroom was in use. The bathroom fans were not of sufficient quality to be operated continuously and they generally had high wattage lamps that were switched with the fan. As a result of the low air change rate, the houses generally exhibited odor problems.

It is not hard to get even better building air tightness than was measured in these houses. However, before any additional effort is made to achieve better airtightness, a strategy needs to be implemented to provide controlled ventilation in these houses. A recommendation was made to the housing authority staff that the existing bath exhaust fans be replaced with high quality bath fans (continuous duty, low energy, low noise), such as those available from Panasonic (recommended model FV-07VQ). If a light is combined with the fan (model FV-07VQL), the light should be switched separately from the fan. The fan should be wired to an electronic timer, such as one available from Tamarack Technologies (Airetrack). The timer should allow fan operation at high speed while the bathroom is in use, and for some time after that, then go back to a lower speed for continuous or intermittent operation. Copies of literature for both the Panasonic fans and the Airetrack controller are attached. 

In an effort to obtain basic energy use and comfort data on the houses, simple energy use and indoor environment instrumentation was installed in two of them. One home was constructed with SIP walls and floor, the other was constructed with 2x6 wood frame walls and concrete slab floor. Since these homes are all electric (no gas or oil), a measurement of hourly average current draw at the main service L1 and L2, and a measurement of current draw of the domestic hot water heater will give us the electrical heat input to the home by subtraction. Any exterior lighting will not be accounted for by this method, but we expect that to be small relative to the total. We will interview the occupants concerning their typical outdoor lighting habits and any other typical electric consumption outside of the house. Indoor temperature is measured in two locations- the kitchen (main area) and master bedroom, and indoor relative humidity is measured in the kitchen. Outside temperature, relative humidity, and horizontal solar radiation is also measured. It is planned that the data will be collected once in the middle of the heating season (January), and once at the end of the heating season (April).

For each of the houses monitored, a building audit was completed for the purpose of energy analysis for peak heating load and heating consumption. This information is given in Table 2. A home energy rating was also computed using the unpublished USDOE method, which is intended to follow the unofficial guidelines of the National HERS Council. The reference house always scores an 80. The EPA/DOE Energy Star program labels a house as Energy Star compliant if the rated house scores 86 or above. The rated house has the equivalent of five percent better energy performance than the reference house for every point above 80 and five percent lower energy performance for every point below 80. As shown in Table 2, the ratings for the two Coquille test houses were 84 for the SIP house and 73 for the frame house. Neither house made Energy Star status primarily due to the use of electric resistance heat. The frame house scored lower than 80 primarily due to the uninsulated concrete slab foundation.

Table 1

where: ELA = effective leak area (in²) calculated at a 4 Pa pressure differential
CFM50 = cubic feet per minute of air leakage at a 50 Pa pressure differential

Table 2