An EPC which is issued by a registered, accredited Energy Assessor and details how energy is used in a property along with an indication of how much the energy bills are likely to be. The assessor will also highlight where possible improvements to the property’s energy efficiency could be made. There are two types of Energy Performance Certificate, domestic and commercial and these require different accreditations to be held by the assessors. A Commercial Energy Performance Certificate can only be produced by a qualified Non Domestic Energy Assessor which is step beyond the accreditation required for a domestic property. 

A Certificate is produced as a result of the findings of a visual inspection of the property by the assessor. It is required if a property is to be sold or let and is valid for ten years. The assessor will look at the heating, lighting and other fixed energy users in the property as well as the existing insulation, windows and doors which may be responsible for heat loss in the property. The assessor will also document the size and construction materials used in the building. 

Heating is the energy using element with the largest impact on you EPC rating and will therefore come under a great deal of scrutiny from the assessor. They will look at the age and type of your heating system as well as how it is fuelled. The number and size of any radiators will be noted and whether they employ thermostatic valves. Is there a secondary form of heating such as a coal fire or wood burning stove?

Today's central heating boilers are much better than the old ones. They can heat water more efficiently, meaning they use less gas or oil to do the same job. This saves energy and will save you money. Replacing an old inefficient boiler will add greatly to your EPC rating.  Also worth bearing in mind is that current legislation will ban the installation of new gas fired boilers by 2025, at which time a heat pump may be required. A new gas boiler installation might cost somewhere between £2000 and £4000 whereas a heat pump installation could be somewhere in the region of £7000 to £13000. Such a price difference may be an extra incentive to replace your old boiler sooner rather than later.

Lighting also has a big impact on energy usage, so the assessor will look closely at the number of fixed lamp holders in the property and will consider the types of bulbs being used. The use of incandescent light bulbs is now being phased out, replaced initially with halogen bulbs and now more often by low power LEDs which give more light for any given power usage. A property with LEDs fitted will use much less energy that one still using the old incandescent bulbs or indeed halogen.

This lower power consumption could also have an effect on the eventual rating on the Energy Performance Certificate, as well as cutting down on energy bills. LED bulbs are more expensive to buy but you will more than recoup the difference in shelf price by way of your saving in energy consumption, with the added bonus of longer LED life which means they will need replacing less frequently. 

Having looked at how the energy consumed in the property is managed, the assessor will turn their attention to wasted energy within the property. How much heat is lost rather than used and how and where that heat is being lost.

Lack of insulation is a major source of heat loss. A house can lose around a third of its heat through an uninsulated loft, meaning it can be more expensive to heat the property and more difficult to keep it warm. Ensuring that your loft is fully insulated by laying insulation that is at least 270mm thick between the joists will help stop a lot of this heat from escaping. Spray foam can also be an effective heat loss barrier, but it needs to be professionally installed, with great care taken to ensure that proper ventilation is maintained.

Insulating outer walls will also lower the property’s heat loss. Cavity wall insulation can be put in place in most reasonably modern properties where the outer and inner walls have a cavity between them. An older property which will have solid stone walls will need to have either an outer layer of insulation applied and covered with some type of cladding or a layer of insulation added to the inner face of the walls. This involves covering the insulation with a decorative finish like plasterboard and means losing a few inches off the dimensions of the room. Cavity wall insulation is easier and less expensive than adding insulation to a solid wall but both are very effective at cutting heat loss for a property, which will improve your EPC rating and cut down your heating costs.

 Glazing and draughty windows and doors will also be scrutinised by the assessor. If a central heating radiator radiates warm air into a room, a single glazed window just as effectively radiates cold air from outside into a room, cancelling out much of the central heating radiator’s efforts to keep the room warm. By installing double glazing, you effectively add a sealed, vacuum filled barrier plus a second sheet of glass between the interior of the room and the cold air outside. This cuts down the heat loss and energy usage substantially, which in turn improves your EPC rating.

The assessor will also look for ill-fitting windows which allow draughts and they will check outer doors which are similarly draughty. It is often simple to fit a draught excluder round an old draughty door as a short term measure, before applying the long term solution of a new door.

Some of these improvements can be expensive, so look at what you can do cheaply before embarking on heat saving projects with long term pay backs, while always remembering that some larger outlays can still make financial sense. The certificate will be accompanied by a list of suggested energy saving improvements with the approximate costings attached to them.

All commercial property being either sold or let must have an Energy Performance Certificate commissioned within seven days of being put on the market with a further twenty one day period allowed for the delivery of the certificate. 

As with a domestic Energy Performance Certificate, a Commercial Energy Performance Certificate is delivered after an assessor carries out a visual inspection of the property. This should contain information about the property’s energy use and typical energy costs as well as recommendations about how to reduce energy use. 

All large public buildings also require to have an annual Display Energy Certificate (DEC) highlighting their energy performance. This is to be displayed prominently in a place visible to the public. Display Energy Certificates measure the actual energy usage of a building based on annual consumption, whereas Energy Performance Certificates measure the energy efficiency of the building based on the type and level of insulation in walls and roofs, and the efficiency of services such as heating, lighting or ventilation.

The energy performance of a property comes under consideration even before it is built. Before construction begins, Standard Assessment Procedure (SAP) calculations need to be completed. This is a standard methodology which will calculate how energy efficient a new build is predicted to be, calculating and determining the energy performance of new build properties, include extensions to existing properties. This assessment will be used to help with the calculation of the EPC rating once the property has been finished.

If you are building a new property or extending an existing one, you will need to have SAP Calculations carried out in order to have a Predicted Energy Assessment and an On Construction EPC Certificate issued.  These are required to comply with Building Regulations and must be completed before any construction work is started.If you want to check the Energy Performance Certificate for your property, please go to the Government website; https://www.gov.uk/find-energy-certificate