Barrie Evans' review of the new econ 19 (aj 19.3.98) on energy standards for offices prompts a couple of responses.
First, on the need for submetering. The guide does suggest that submetering is worthwhile to allocate costs correctly, and the structure of the main tables with the split by end-use guides the reader towards collecting the data this way.
Second, on the issue of space-use intensification, where an office which is more efficient in space-use terms may be penalised for its higher energy use per square metre. The guide is meant for people to gauge their building's performance against that of the typical office in the market, with encouragement through the readily achievable good practice benchmarks.
We did consider normalising for occupation density and hours of use (which would have answered his comment), but past experience has shown that there is too much scope for the non-technical reader to misunderstand the figures. How does the designer benchmark an office intended for 50 people where later the actual occupancy varies between 10 and 45? There are some features whose energy consumption varies with the number of people, but many others which carry on regardless of the number of people actually present. So, on balance, we stuck with a less ephemeral denominator - the treated area.
Benchmarks are not rules, so there is nothing to stop the office building consuming more than the area-related figures if the increase can be justified. It's up to the reader to mount an argument which convinces the client and peers if he or she wants to adapt the econ 19 benchmarks. The appendices provide information which helps to do this.
In fact we would be very pleased if architects did have discussions with their clients about energy benchmarking in existing or proposed buildings, because it would raise the issue and keep it in their minds in future.
Project manager, brecsu