What Is an Energy Performance Certificate (EPC)?

Property Information

The details of the property for the certificate, are at the top of the page. The date of assessment/certificate are included, worth noting as a certificate expires after ten years.

The reference number is the unique number for your certificate and it can be used to search on the EPC register to ensure that the certificate is authentic.

Standard Assessment Procedure (SAP) is the term used for how the government measures the energy efficiency of a building and compares buildings with each other (to inform reports and policies). The SAP assessment is based on standard (not actual) occupancy and behaviour for homes, so that properties can be compared like-for-like.

• RdSAP is a Reduced data SAP and is used for existing properties.
• SAP is used to assess newly built properties.

Estimated Energy Costs

The energy costs for lighting, heating and hot water are calculated and displayed in a table.

These costs are calculated from several factors in your property, which are outlined under the summary of the home’s energy performance related features such as: the heating system in the property; the insulation efficiency of the walls, roof, windows and floors.

A standardised occupancy and behaviour is used to make the calculation, such as how many people live in the property, how many baths or showers they have and for how many hours a day the heating is switched on. This allows properties to be compared like-for-like. The energy bill calculation only includes heating, hot water and lighting and not electricity used for any other purpose such as TV, laptops or cooking.

For example, two properties, semi-detached, with floor space of 135-144 m2, the estimated energy costs for heat, light and hot water:

• An A rated home costs a total of £1,701 over three years – equal to just under £45 a month.
• A G rated house costs a total of £11,010 over three years – equal to just over £300 a month.

Energy Efficiency Rating

The rating for the property is displayed in a similar style to the energy efficiency rating for home appliances (such as fridges). This is a colour coded visual that’s quick and easy to understand.

The certificate indicates what the score and band rating for the property is, from A to G.

A is the highest rating, meaning a property is highly energy efficient and G is the lowest and least energy efficient, with potentially high energy bills.

Rating is based both on the energy use per square metre of floor area (this is noted under the summary of energy performance on page three) and the energy efficiency measured by fuel costs.

The rating also shows the potential score you could achieve if the recommendations on the certificate are applied.

For example, two properties, semi-detached, with floor area 135-144 m2

• A rated score of 95 with a potential to achieve a 96 (by installing solar water heating).
• G rated score of 11 with a potential to achieve a 76 (by implementing all the recommendations).

Top Actions/Recommended Measures

On the front of the certificate is a table of the top actions you can take to save money and to make your home more efficient.

This is a summary of the full list of recommendations that are shown on page three.

Summary of Energy Performance

This table shows the different factors in the property that are assessed for energy efficiency and is useful to review the areas of your property and how they were measured.

Each factor, such as, heating, lighting and insulation are measured by a five-star rating of energy efficiency. For example

• A rated property has high performance glazing – 5 stars
• G rated property has double glazing – 3 stars

The insulation of the property is measured by a thermal transmittance rating that indicates the heat loss through walls, floors and the roof. Any insulation in the property must be visibly inspected in the assessment to be included. If it can’t be accessed (for example, cavity wall insulation) then documentation of evidence must be produced.

If the certificate states ‘Assumed’, this means that the area could not be visibly inspected and there was no evidence of insulation, so the assessment is marked as not insulated (whether there is insulation, or not).

Air tightness is measured on all domestic properties and large extensions built since 2006 (Building Regulations Part L). An air permeability test of the property for leakage through walls, windows, doors and floors is an indication of energy efficiency. For all new dwellings since 2006, this is marked on the certificate but for all existing dwellings older than 2006 this isn’t included or required.

Underneath the table is the primary energy use per square metre that’s used in the calculation of the EPC rating. For example

• A rated property – 15 kWh/m2 per year.
• G rated property – 913 kWh/m2 per year.

Heat Demands

The heat demand table indicates how much energy is used to heat the space of the property and to heat the water And is measured based on a standard occupancy and usage.

For example

• A rated – space heating – kWh per year – 5,371
• G rated – space heating – kWh per year – 37,973

On the G rated property, the table also highlights how much impact having insulation in the property can make to the energy used in heating the space of the property.

Recommendations

The recommendations table is so important because it breaks down how much your EPC rating can be improved, what the costs to make the improvements are and as a result, how much of a saving you can make on your annual energy bill. This will help you to make an informed decision on what changes you should be making.

The lower the rating on the certificate, the more attention you should give to the recommendations section as this could make a significant difference to the value of a property.

The recommendations in the table are made in cumulative order, this means that in the table, the potential improvement rating shown in the right column is only applicable if all the improvements up to and including that row are made.

You’re not legally obligated to make changes recommended.

For example:

The G rated property has nine recommendations that could take the property from a G11 rating to a C76 – a huge increase of 65 points. But, to achieve this would be a cost of up to £51,640 to result in energy savings of £2,910 per year (payback of 18 years). Cost effective?

To take the property to an E rating and an increase of 38 points would be a cost of up to £12,640 resulting in energy savings of £1,870 (payback of 7 years). A more reasonable achievement and would take the property to the minimum rental rating.

The A rated property has one recommendation of solar water heating. At a cost of up to £6,000 this will only make savings of £51 and an improvement of one point to A96 on your EPC. Probably not an investment worth making.

Environmental Impact (CO2) Rating

In response to the Kyoto Protocol and the UK's commitment to reduce emissions, more awareness has been made about what contributes to climate change. As a quarter of all CO2 emissions in the UK come from the energy we use to heat and light our homes, the EPC is all about helping to reduce carbon emissions. The average house contributes about 6 tonnes of carbon dioxide every year.

The impact of buildings on the environment used to be shown on the front of the certificate alongside the EPC rating. This has now been moved to the last page, most likely because displaying the two graphs next to each other was confusing and also, the environmental impact rating had no context for most people.

As the overall focus of an EPC is about reducing emissions, the environmental impact is actually the most important rating on the certificate but has the least meaning to most people. A higher rating means that a property has less impact on the environment. For example:

• The G Rated property has a 1-point (very low) rating and produces 21 tonnes of CO2 in a year.
• The A rated property has a 94-point (very high) rating and produces 0.4 tonnes of CO2 in a year.