Monthly air-conditioning energy demand calculations for building energy performance rating

Abstract

A new calculation method for monthly cooling energy demand is presented which extends the utilisation factor method of standard EN ISO 13790:2008 to take account of a number of important features of air-conditioning systems that are currently ignored. In all other respects it is compatible with this method, which is the most widely used means of producing building Energy Performance Certificates in Europe. In particular it enables the impact of free cooling, and of the tempering of supply air to be quantified; calculates tailored seasonal efficiency figures for chillers, and provides initial estimates of the potential savings of inter-room heat recovery and of the energy penalties associated with terminal reheat and dual duct systems.

Practical application: This paper proposes an extension to the most widely used calculation method for Energy Performance Certificates in Europe, improving its ability to reflect important features of central air-conditioning systems. This is of particular importance for climates and buildings where cooling is required when the outdoor air temperature is relatively low. In particular it enables the impact of free cooling, and of the tempering of supply air to be quantified, calculates tailored seasonal efficiency figures for chillers, and provides initial estimates of the potential savings of inter-room heat recovery and of the energy penalties associated with some other systems.

Keywords

Air conditioning energy calculation energy performance rating

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