So, Arup finds the SBEM software, which shows that more glazing results in lower energy consumption, "counter-intuitive" (BSj 02/06)? Well, perhaps that just goes to show how unwise it is to rely on intuition.

The fact that a highly glazed office building can be more energy-efficient than one with parsimonious levels of glazing should come as no surprise to those who are aware that glass is a unique material, and able to transmit free solar heat and daylight into buildings. Assuming that the built form, materials and energy management system are designed to take advantage of this energy, a better and more energy-efficient building will be the result.

Think about it: if glass didn't gain more energy than it loses, a solar collector or a sunspace wouldn't work. That's why almost every exemplar low- or zero-energy building you will ever see has copious amounts of glass.

The philosophy behind the new Part L is to be welcomed. It moves us on from the old approach of prescribing the U values of each element, to a system where the total energy performance of the building is what matters. In conjunction with the SBEM tool used to demonstrate compliance, the new Part L should be a liberating development for designers. Certainly, it will enable the positive energy benefits of large areas of glazing to be modelled and will enable the designer to incorporate them in a Part L compliant building.

Rick Wilberforce CEng MCIBSE

Source

Building Sustainable Design