ABSTRACT:

The famous Howard Davis House in Eugene, OR was investigated to reveal its thermal comfort characteristics and potential to benefit from the addition of thermal mass. Preliminary investigation revealed a tendency for both overheating in the summer and rapid cooling in the winter; in addition, the house has abundant south-facing glazing and minimal southern shading, suggesting that an abundant solar resource was available.

From February 17-21, 2006, Hobo dataloggers were used to assess thermal comfort parameters during normal use. While positions in direct sun fell transiently within ASHRAE 55-2004 thermal comfort standards, both upper and lower levels of the house were cooler than ASHRAE 55-2004 standards for more than 80% of waking hours. Nevertheless, the house was perceived to be thermally comfortable at these lower temperatures, presumably due to a combination of clothing level and activity of the occupants as well as mean radiant temperatures of the surfaces.

Estimations of the house’s solar resource, obtained by location-specific solar incidence information, the ratio of southern glazing area to floor area, published design recommendations, and shading mask mapping, indicated that thermal mass had good potential to mediate internal temperature variation by storing incident solar energy for release during cooler periods.

From March 9-15, 2006, dataloggers were reintroduced, active heating was discontinued, and one ton of thermal mass was positioned adjacent to the greatest area of southern glazing. Variation in internal temperatures subsequently diminished from 57% of external variation to 16-37% of external variation, corresponding to a diminution of absolute variation of internal temperature from 5.25°F to 2.25°F. While the added mass was less than half of that recommended for such a house, the strength of its effect showed that the house would respond quite favorably to this approach.