Air conditioning need not cost the earth

When considering the design of a new commercial office building, in particular the design of the HVAC (heating, ventilation and air conditioning) and lighting system, solar shading should be on the top of the list of priorities. By regulating solar heat gain and controlling light levels shading has a considerable impact on the energy needs of a building.

A recent study carried out by REHVA (Federation of European Heating, Ventilation and Air Conditioning Associations) and supported by ES-SO (European Solar Shading Organisation) compares the capital and recurring costs for HVAC and lighting for two different specification office scenarios:

• Without Shading: With solar controlled glazing installed
• With Exterior Shading: A combination of double low-e glazing and external shading

The studies were carried out for three climate locations but for the purpose of this article, we will review the findings of Amsterdam as the weather conditions there are not too de-similar to that of the weather conditions in the southern parts of the UK.

So firstly lets look at capital costs...By installing exterior shading these were reduced by just over 1%. This is primarily down to a large reduction in the cost of glazing; double low-e ‘v’ solar control (and let’s not forget the difference in the embodied carbon) and an 18% cost saving on the HVAC system.

However, more importantly are the ongoing recurring costs. With external shading installed, there are yearly energy running cost savings in the region of 20% against not having shading. By effectively controlling solar heat gain and light levels, there is big positive impact on the cooling, heating and lighting demands.

All in all this means that correctly specified and installed external blinds will significantly reduce the ongoing energy running costs associated with cooling, heating and lighting, whilst having a simple payback period of…. well zero, as there are no increases in capital costs.

On a final note it is important to remember that every scenario and application will vary as HVAC systems, lighting & external blinds come in different styles, designs and qualities, however, one thing is for sure, external shading does not cost the earth, literally!