CIBSE's low energy opportunity

The report on the conference in November's Building Services Journal reiterated the point made in our paper that the accuracy of computer design tools is dependent on users' experience. The report also reminded us of the ground-breaking research carried out five years ago that revealed the fallibility of such models.

The research referred to highlighted a lot of issues: accurate convective coefficients are important for predicting results for test cells; different simulation programs using different methods for calculating convective and radiative heat transfer coefficients; complex interacting energy flow-paths occur in buildings; accurate measured data is required for comparison with the simulation results. But probably the most important issue is that validation is necessary to have confidence in building services design calculation methods.

The invitation from the Environment Minister Michael Meacher to CIBSE to devise an action plan on energy efficiency emphasises the important role that CIBSE is expected to play. This opportunity should not be wasted.

One of the critical issues for CIBSE is to recommend an accurate method for building services engineers to use in designing low energy buildings. The traditional methods (steady state heat loss and admittance heat gain) need to be validated bearing in mind that Crozier reported at the 1999 National Conference that 100% of cooling systems had more capacity than required. The chiller oversizing factors varied from 1.4 to 4.5.

In Ireland we found boiler plant with over capacity of 227%. This point was also echoed in the proposals for amending the energy efficiency provisions in the Building Regulations.

To seize the opportunity offered by the Minster to improve the sustainability of buildings we must use accurate validated methods to design all buildings.