Abstract | The energy savings attributable to efficient lighting and office equipment technologies are often quoted for the technology in isolation. However, the reduced heat generated by energy-efficient lighting and office equipment will also have an impact on the cooling and heating requirements of a building. Thus, the actual energy savings could be higher or lower than the direct electrical savings of the energy-efficient technology in isolation. This study predicts overall energy savings using DOE-2.1E simulations of a typical officebuilding in six North American climates. We performed a variety of parametric simulations, and the cooling and heating energy impacts were expressed as a fraction of the direct electrical energy impact (ACIAL and MAL, respectively). For each city, ACIAL varied little with the source of the direct savings (lighting or office equipment), building envelope variations (U-value and solar aperture), or the magnitude of the directsavings (up to 54.1 k w ) . Whether the source of the direct savings came from power density reductions or zoning/control strategies also had only a small effect However, cooling system type (economizer or futed outdoor air) had a large effect. H A L varied substantially with envelope U-value, solar aperture, and the magnitude of the direct savings. In the case of cooling, our results agree well with a previously publishedsimplified method for calculating the overall impact of lighting power density reductions, and offer the potential to expand the scope of the method. However, our results suggest that in the case of heating this simplified method may not be generally valid. Note, though, that our conclusions are based on the assumption of a VAV system with economizer, and that a strong dependence on system type is expected. Our work also led directly to a new method of generating lighting power demand profiles for office buildings,and this new method is referenced. |
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