We present a simple model to calculate the energy loss by free cooling at night. The time dependence of the exhaust air and wall surface temperatures is predicted by a simplified dynamic model that couples air flow, heat transfer, and wall temperature. For given ventilation rate the model predicts that the total heat extracted from the building during the night can be maximized by increasing the heat exchanging surface area and the thermal effusivity, of the wall materials. The influence of ventilation rate on the heat removed by freecooling at night is discussed.
Night cooling is a viable technique in the UK, but there is no suitable commercially available equipment. The BRE has been testing prototype ventilators and concludes that they work although weather, security and acoustics issues need to be addressed.
How do tenants of public housing respond to retrofits to improve their comfort and energy use during the cooling season? In contrast to retrofits to improve heating or lighting, cooling retrofits have been little studied, despite extensive programs by utilities and housing authorities to reduce this end use. A local utility and a housing authority have been retrofitting their buildings with evaporative coolers, ground-source heatpumps and other cooling measures.
There are many hurdles in the road to widespread adoption of energy-efficient heating and cooling (HVAC) equipment in homes. These hurdles include increased first cost, lack of sufficient financing, historic lack of aggressive marketing by HVAC equipment dealers, and lack of consumer awareness. This paper reports on the design and progress of the ENERGY STAR market-based approach to overcome these hurdles to encourage the widespread manufacture and purchase of highly efficient heating and cooling equipment.
Manufactured homes, often referred to as HUD-code homes, are continuing to grow in importance as a national housing resource and represented 23% of all new home construction in 1995. In spite of groundbreaking work to characterize the performance of air distribution systems in site-built housing, in new manufactured homes, the subject has been largely ignored. Field data was gathered from 24 typical new HUD-code homes in four regions in the continental United States. This study describes air distribution system losses estimated through an analysis of system and distribution efficiencies.
This paper examines key issues involved in evaluating benefits of tree planting programs from the perspective of electric utilities, as well as from a wider perspective of public and private entities that may benefit from such programs. The nation's largest shade tree program, sponsored by the Sacramento Municipal Utility District (SMUD) in collaboration with the Sacramento Tree Foundation (STF), is used as a case study.
Occupant controlled HVAC systems offer inhabitants of open office spaces some degree of control over their immediate microclimate typically by control of air supplied at floor or desk top level. Productivity gains have been attributed to these systems but it is unclear whether these systems will use less energy than conventional HV AC systems. It is also not clear what the controlling parameters will be. To study energy consumption, a simplified model of the thermal environment was created for an occupant controlled system.
This paper reviews the development of performance indices for fabric thermal storage from the original BRE office research data to the two mixed mode design options currently available, each having different design priorities, namely naturally ventilated or mechanically ventilated. Naturally ventilated mixed mode designs appear to be less suitable for UK locations and also appear to have significantly greater annual energy consumption. In addition to the comparison of energy consumption criteria, the paper also reviews recent Scandinavian indoor climate classifications.
A five-year initiative between the U.S. Department of Energy (DOE) and the U.S. Department of Housing and Urban Development (HUD) demonstrated the feasibility of improving the energy efficiency of publicly assisted housing. Twenty-seven projects and activities undertaken during 1990-95 involved research and field demonstrations, institutional and administrative changes to HUD policies and procedures, innovative financing and leveraging of federal dollars with non-federal money, and education, training, and technical assistance.
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