Background
It is difficult to explain the rationale behind the introduction of commercial EPC's without referring to man made global warming which is widely believed to be a consequence of the Greenhouse effect causing a build up of carbon dioxide in the atmosphere.
The Greenhouse effect was first discovered by Joseph Fourier, a French mathematician, in 1824. Since then things have got worse. A lot worse. The first World Climate conference didn't take place until 1979 and a combination of a lack of political will; commercial interests and disagreements amongst climatologists meant that a further eighteen years passed until the Kyoto Treaty started the ball rolling to the point that we have now reached. Most of the world's climatologists are now signed up to the view that carbon emissions caused mainly by mankind burning fossil fuel, are causing the average temperature of the world to rise.
Predictions about how far temperatures will rise and how quickly vary enormously, but there seems to be little doubt that the effect is real and that the world is heading for disaster unless we do something dramatic to cut our carbon emissions. The present global economic downturn may well be having a positive short term effect, but at best it is likely to prove to be only a breathing space to allow us to get our collective act together.
Commercial or non-domestic buildings are responsible for almost 20% of the UK's energy consumption and carbon emissions, so when the Government signed up to the Kyoto Protocol and committed us all to reducing our carbon emissions by 60% by 2050 it was inevitable that the commercial property industry would be expected to do it's bit.
Even now, of course and despite the mounting evidence in favour of the majority view that climate change is a reality, there are still those who think it's all part of a conspiracy. Naturally, you won't find too many Commercial Energy Assessors holding this view.
When we buy a new car or fridge these days we are confronted in the showroom by one of those colourful charts telling us how energy efficient the product is on a scale of A to G. The rating is designed to help us to decide which product to buy on the basis of the cost of running it. In theory we will pay more for a product that will cost us less in the long term. Therefore, demand for more energy efficient products should rise over time and manufacturers will be persuaded to continually improve the energy efficiency of their products. The other side of the equation is, of course, regulation, whereby the Government forces manufacturers to reduce carbon emissions from their products.
The same principle lies behind commercial EPC's, but unfortunately there is no easy way to calculate the amount of carbon likely to be produced by a commercial property. The Government has an excellent tool at it's disposal when we want to construct a new building or when we want to alter or extend an existing building - they use Building Regulations to force us to insulate our buildings better. However, it's much harder to force businesses to use less energy in existing buildings that are not going to be knocked about.
In order to resolve this problem and to enable people to start giving more thought to the energy efficiency of commercial buildings and hopefully to base their purchasing and leasing decisions at least to some extent on this factor, the Simplified Building Energy Model or SBEM for short was devised and Commercial Energy Assessors came into being.
SBEM
SBEM has been formally adopted by the Government as it's means of complying with the EU directive. SBEM is the tool that Commercial Energy Assessors use to calculate the rating that you see on an EPC (Level 3 and 4).
The great problem with trying to assess the energy efficiency of buildings and in comparing one with another is that the amount of energy likely to be used is at least as dependent upon the people in occupation and how they use the building as it is on the building fabric and the means of heating and lighting it. SBEM attempts to deal with this problem by comparing similar buildings with each other, so that shops are compared with shops and so on, but inevitably the process if far from perfect. Commercial Energy Assessors use SBEM to prepare each commercial EPC to Level 4.
Calculating how much carbon is likely to be pumped into the atmosphere by a new car is much easier than trying to work out how much will be produced even by two identical properties standing standing side by side. Probably the only significant variables in respect of the car are how, when and where it is going to be driven, but for the building there are a lot of different factors at play. Moreover, the quality of the information entered into SBEM by Commercial Energy Assessors to produce a Commercial EPC is crucial to the end result.
The data collection process for a commercial EPC is far more complicated than simply measuring the floor area, as Chartered Surveyor's would do for most commercial valuations. Commercial Energy Assessors need to calculate floor areas, but we also need a lot of other information such as wall heights; window sizes; the direction the building is facing; the type of lighting in use; the type of heating, air conditioning and ventilation; the method of heating water and the nature of the construction from top to bottom including the windows and the doors.
It is estimated that heating accounts for about 55% of energy use in commercial buildings and lighting around 25%, so these are generally the most important factors determining the energy rating.
Once Commercial Energy Assessors have gathered the information required, or made appropriate assumptions if we are unable to find everything we need, we are required to split the building into zones according to use; lighting and means of conditioning. Usually, the most complicated buildings are offices that are split into lots of small areas. Finally, Commercial Energy Assessors enters the data into the SBEM calculation engine and a commercial EPC rating is generated.