House/home energy rating schemes / systems (HERS)

Abstract

HERS are methods of rating the energy performance or energy-efficiency of a house by calculating (usually incorporating a computer simulation) the energy load and/or energy consumption of a dwelling for several end-uses such as heating, cooling and water heating. Inherent in all the methodologies is the assumption of ‘typical’ occupant-related factors such as number of people, number and use of appliances, and thermostat settings. The climate used in the calculations is also standardised for a given location. Typically a HERS rating is expressed as a number of points or a number of Stars. A house rating however, has many potential sources of error such as inaccurate calculation algorithms, incorrect assumptions about the physical properties of the building, wrong assumptions concerning the operation of the building and finally mistakes in data entry to the computer program. Given the apparent importance placed on HERS in national greenhouse reduction policies it is surprising to find so little written about them and almost no work that investigates the claims that HERS save energy and costs and reduce greenhouse gas emissions. This paper describes research in Australia that has attempted to correlate the rhetoric of HERS with reality. The results have possible implications for all HERS.