Lawrence Berkeley
National Laboratory
Environmental Energy Technologies
Indoor Environment Department
Energy Performance of Buildings Group

Introduction

Energy and resource efficient building conditioning uses alternatives to conventional heating and cooling sources. In non-residential buildings, the power to operate the compressor at design conditions amounts to approximately 2/3 of the electrical power requirement for an all-air system. Therefore, replacing motor-driven compressors constitutes in a significant energy conservation measure and peak-power reduction potential.

Before applying energy-efficient systems, the following steps should be taken:

1. the building envelope has to sufficiently separate the conditioned space from the ambient influences (high thermal insulation and blockage of irradiation)
2. internal loads have to be reduced by improving the lighting efficiency and by use of efficient equipment (plug-load)
3. thermal storage has to be implemented to reduce the amplitude and to phase-shift loads into unoccupied hours
4. the building’s thermal distribution system has to be optimized by separating the tasks of ventilation and thermal conditioning
5. the equipment used to transport air and water through the building as well as their electric motors have to be designed to operate at high efficiency.

Only after these steps have been taken, energy efficient systems can effectively perform their task.

We see that energy and resource efficient building conditioning is, in general, a result of a combination of architectural design, the selection of materials, equipment, HVAC technology, and the energy source. However, the main general concern is not the "energy" itself, but the environmental impact, which is caused by the use of energy to operate the building, to produce the materials and the systems, by the building process, and also the use of other precious resources, e.g., water to be used to be evaporated for cooling purposes. Alternative building conditioning systems generally result in a reduced energy consumption during operation, but often cause an increased material input. It is therefore essential to make an integral assessment of the factors influencing the environmental impact of such systems. An assessment has got to be based on a life cycle inventory, concerning all relevant substances and effects, and should take care of the real configuration and of the annual performance of such systems including the human behavior.

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Last update of this page: March 11, 2004