Space cooling is a major contributor to electric utility peak loads in the Southwest. In Arizona, electric utilities typically reach their summer peaks in late afternoon, when temperatures often exceed 100deg.F. Residential conservation measures focused on space cooling can reduce costs associated with these peaks, by allowing utilities to avoid burning fuel in their most expensive units and to defer additions to generation, transmission and distribution capacity (Shuman, 29).
Study was conducted of 149 houses in the Phoenix, Arizona, area to find out which conservation measures are most effective in reducing space cooling loads. Houses were audited, observed hourly whole-house electricity usage for one year, installed one or two space-cooling conservation measures in each study house, and observed electricity usage for another year. Then regression analysis was used to study the change in electricity use from the first year to the second, taking into account weather, structures and occupant characteristics. The conservation measures, installed were: higher-efficiency heat pumps or air conditioners that replaced old models, efficient evaporative-cooler motors, pre-coolers to evaporative cool intake air of existing air conditioners, trees to shade sun struck sides of the house, increased attic insulation, interior "storm" windows, flat roof reflective coating, and sunscreens. It was found that the largest savings (in increasing order) resulted from shade trees, attic insulation, more-efficient heat pumps or air conditioners, and pre-coolers (Young, 16).
It also found that power and energy savings could be increased via targeting the types of houses for retrofit. Two factors are important in targeting houses in the desert Southwest: the type of cooling system (an air conditioner or heat pump only, versus dual cooling systems with both evaporative cooling and either an air conditioner or heat pump), and the energy efficiency of the house prior to installing conservation measures ((O'Connell, 19).
Less-efficient houses can....
