DOMESTIC HOT WATER CONSU1\1PTION IN FOUR LOW-INCOME APARTMENT BUILDINGS Edward Vine, Rick Diamond, and Rich Szydlowski Lawrence Berkeley Laboratory
ABSTRACT Domestic hot water consumption is a major source of energy use in multifamily buildings. In contrast to space heating energy consumption, in which behavioral factors compete with the effect of climate, domestic hot water consumption is highly dependent on behavior. Consequen tly, knowledge of usage patterns is useful in understanding domestic hot water consumption, whether for calculating baseline usage or for estimating retrofi t performance. We investigated domestic hot water consumption in fOUf apartment buildings (a total of 48 units) managed by the San Francisco Public Housing Authority. In each of the buildings, we monitored the performance of the domestic hot water system for six months, and interviewed the residents about their hot water usage patterns. We found the shape of the measured profiles of daily domestic hot water consumption to be different from profiles published in the literature. We constructed a model of household water consumption based on reported behavior, and found occupant-reported water consuming behavior to correspond well with measured data: building differences ranged from -19% (the model underpredicts) to 12% (the model overpredicts), and the average difference was approximately 12%. We found educational status to be the only significant sociodemographic predictor of estimated household hot water consumption.
DOMESTIC HOT WATER CONSUMPTION * IN FOUR LOW-INCOME APARTMENT BUILDINGS Edward Vine, Rick Diamond, and Rich Szydlowski Lawrence Berkeley Laboratory
INTRODUCTION In this paper, we examine domestic hot water consumption in four low-income apartment (multifamily) buildings. We have chosen this topic for several reasons. First, hot water consumption represents a significant use of energy in multifamily buildings: approximately 30% of national multifamily energy use ~ for domestic hot water consumption (in comparison to 15% in single-family houses). This percentage is greater in cases where space heating needs are smaller-for example, in mild climates, and in new, thermally-efficient buildings (U.S. Department of Energy, 1985). Second, while behavioral factors compete with the effect of climate in driving space heating energy consumption, domestic hot water consumption is highly dependent on behavior. Hot water consumption is often influenced by cultural and social norms: American households use seven times the amount of hot water used by households in some industrial European countries (Schipper, 1982). In addition, in apartment buildings where hot water is typically master-metered, occupants have no economic incentive to conserve, and, therefore, hot water consumption can be relatively large as well as idiosyncratic. For example, in France, consumption of hot water in apartments with master metering may be as much as 50% larger than consumption in apartments with individual metering (Compagnie Generale des Eaux, 1970). Similar numbers have been observed in West Germany (Cae, 1978). And third, knowledge of usage patterns is important in understanding domestic hot water consumption, whether for baseline usage or for estimating retrofit performance. There is currently very little information on how much energy is used for particular functions (e.g., heating, cooling, domestic hot water, cooking, and ligh ting), an(fJ
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