Energy Performance Certificates Frequently Asked Questions


The information applies to current legislation, methodology and EPCs.

1. What is an energy assessment?

A Bluewire Hub Energy Assessor will visit your property to collect the data required for assessing the properties energy features, and using this information produces an Energy Performance Certificate (EPC) using government-approved and accredited EPC software. The assessment is based on the age, construction, dwelling type any and relevant fittings such as heating systems, insulation or double glazing. Please don't confuse an Energy Performance Certificate survey with a structural or building survey, condition report or property valuation. An Energy Performance Certificate is not a report on the condition of the property nor will it comment on the presence or otherwise of asbestos, high alumina cement concrete, additives including calcium chloride, or any building defects or hazardous materials. An EPC does not cover items or problems in the property which may be picked up in a building survey, which could be costly to rectify, these are outside the scope of the data collection methodology of an EPC.


2. How do I check that an EPC is valid?

Go to The EPC Register  click on 'Retrieve Report Using Property address and follow the instructions on the screen. Alternatively get in touch and we will do the research for you.


3. Why are the potential heating costs greater than the current heating costs when the EPC recommends low energy lighting is installed?

This occurs when low energy lights are recommended by the Energy Performance Certificate and there is no recommendation for improvements to the heating system. Standard light bulbs generate more heat in use than low energy light bulbs so if you are replacing your standard bulbs with low energy bulbs the heat generated by the lighting is reduced. The EPC software will adjust the heating system demand to make up the difference. The reduced lighting cost is greater than the increase in heating cost giving an overall net reduction in energy costs for the property.


4. The costs shown on the EPC are higher/lower than my actual energy bills for the year, why is this?

Energy Performance Certificates use standardised assumptions to make properties directly comparable while still reflecting the features of individual properties. The EPC costs are based on a number of set assumptions which are as follows;

Standardised heating pattern

Set number of occupants

Standardised hot water usage.

These assumptions can vary appreciably between different households even if living in similar properties. Our trained assessors are happy to discuss ways that you can improve your energy usage after the survey has been completed.


5. My property is maintained to a high standard; surely the rating should be higher than shown in the report?

The Energy Performance Certificate survey does not reflect the current condition of fabric, fixtures or fittings, nor is it indicative of the decorative state of the property.

The purpose of the EPC is to give information on the current and potential energy performance of the property.


6. I have added insulation to my house, but the rating is low and the insulation is not shown on the EPC, why is this?

The energy assessment is a non-invasive survey and our assessors cannot drill holes or remove inspection covers to assess levels of insulation. For Loft, Flat Roof, Floor, Solid Wall or Cavity Wall insulation to be included in the assessment there must be evidence, visual or documentary, of specific works relating to the property being assessed. If insulation has been added but there is no access for the energy assessor to observe it or relevant documentary evidence such as a guarantee or building control notice, it cannot be included. In these cases the level of insulation is assumed  to be the relevant building control standard based on the age of the relevant part of the dwelling. This applies to any roof insulation, floor insulation and wall insulation.


7. Why is the heat demand not the same as the “primary energy”

A home’s heat demand is the amount of energy the property would require to heat it to “standard” occupancy levels and to provide hot water. the efficiency of the heating system is not considered.

Primary energy is a measure of the energy required for any lighting, heating and hot water, taking account of the efficiency of the heating system (and the power station efficiency in the case of electricity) and the energy expended in extracting the fuel from its source and in conveying it to the dwelling.


8. What does the summary of this properties energy performance related features show?

This is a summary of the dwelling’s energy performance rating. Each element of the property (walls, roofs, heating system, etc.) has been rated between one and five stars based on its energy efficiency, one star is the least efficient and five stars the most efficient. The EPC rating is assessed by the accredited software on the based on the age of property, the construction type and any relevant features. The EPC rating relates to energy efficiency and not appearance. It does not take into account the physical condition, function or quality of the areas assessed.


9. Why do some elements in the “Summary of the energy performance related features” table not have a star rating?

A star rating for secondary heating, such as a gas fire, is not shown in the “summary of the energy performance related features” because no recommendations are made for improvement of secondary heating. A star rating for floor insulation is not shown because the thermal performance of the floor depends not only on the construction and insulation levels but also on the size and shape of the floor, so that comparison between different properties is not meaningful.


10. An ‘indicative’ cost is shown for recommendations on my EPC, what does this mean?

The indicative cost of EPC recommendations are those that apply to a typical property of this type. They may differ for very small or very large properties or ones with special features such as solar panels. The cost data is compiled by the Energy Saving Trust from various sources including EST's Housing Model and Low Carbon Building Programme Analysis.


11. The summary section of the EPC shows a performance rating of only 1 or 2 stars for one or more elements – what does this mean?

The EPC Energy Efficiency performance rating shows the extent to which the element contributes to the fuel costs of the property. If an element has an energy efficiency performance of 1 or 2 stars this means that it results in higher than average fuel costs. This relates to energy efficiency, not appearance. It does not take into account the physical condition or quality of the element. It is an indication of how much more (or how much less) the home will cost to run than an average similar property.


12. I have what I believe to be a highly efficient LPG/oil heating system in my property. However in the summary section of my EPC my ‘Main Heating’ has an ‘energy efficiency’ of only 2 or 3 stars – why is this?

The ‘Energy Efficiency’ column in the EPC summary sectionis related to the cost of running the heating system in the property. This takes into account a three year rolling average price of the fuel used and the efficiency of the heating appliances. The Energy Efficiency column informs the occupier about the heating system purely from a cost perspective. The descriptions in the column therefore change depending on the fuel used and the efficiency of the heating system. For example, a gas condensing boiler will have 4 or 5 stars, whereas an oil boiler of the same efficiency will have 3 and an LPG boiler of the same efficiency will have 2.


13. I have a very modern electric heating system in my home. However, in the summary section of my EPC ‘Main Heating’ has an energy efficiency rating of only 1 star – why is this?

The Energy Efficiency column in the summary section is related to the cost of running the heating system. This takes into account the price of the fuel used (per kWh) and the efficiency of the heating system. Electricity is significantly more expensive than mains gas, which is one of the cheapest forms of fuel. For example a mains gas boiler will cost less to run than an electric boiler or electric storage heaters regardless of the age of the heaters. The Energy Efficiency column informs the consumer about the heating system purely from a cost perspective. The ratings in the table will vary depending on the fuel used and the efficiency of the heating system. Even though an electric heating system may be 100% efficient at the point of use, turning all the electricity used into useful heat, it will still be more expensive for a home owner to run than a 65% efficient mains gas boiler. A gas boiler will have heat losses associated in converting the burning fuel into useful heat for the property, but these losses are outweighed by the lower cost of mains gas.


14. My property is heated by conventional electric heaters and the EPC recommends the installation of storage heaters. The resultant change makes the Environmental Impact Rating worse rather than better – why is this?

Storage heaters are recommended as they are cheaper to run, making use of low-rate night-time electricity. However the total amount of electricity used by a storage heater system is greater than that used by conventional panel heaters. Therefore the resultant Energy Efficiency Rating on the EPC is improved as running costs are reduced but the Environmental Impact Rating is made slightly worse as the total amount of energy used increases.


15. My recent EPC makes the recommendation of changing my current boiler to a new condensing boiler, but I have only recently had my boiler changed – why is this?

The EPC provides an indication of the potential energy performance of the property and in this case has identified that the current boiler is not the most efficient boiler available. The recommendation to improve the boiler to a more energy efficient boiler is made purely on the energy efficiency rating of the boiler and is not a reflection of the age or condition of the currently installed boiler. This recommendation identifies that there are more efficient boilers available and that a homeowner should consider this when they next have to replace the boiler.


16. My EPC lists a number of recommendations that seem inappropriate as they suggest changing items that I have recently updated, renovated or replaced

The Energy Performance Certificate identifies the current and potential energy performance of the property but does not take into account the age or physical condition of any of the elements assessed.


17. These FAQs have not answered my question. What can I do now?

In the first instance contact your energy assessor, whose details can be found in the ‘About this document’ section of the EPC. If our assessor is unable to resolve the issue to your satisfaction, contact our head office in the first instance, if we are unable to help you can contact our accreditation scheme here.


The information provided applies to current legislation, methodology and EPCs.

We have used the team at Bluewire Hub now for some years and would strongly recommend them. We receive a superb service from a friendly team, who are always eager to help. Their contact and approach with our clients is always professional and regularly mentioned by our Vendors and Landlords. 5* service from start to finish.

Craig Bees, Bartrams Estate Agents, Towcester

Domestic EPC

Bluewire Hub Ltd can provide Estate Agents and homeowners with a quote for your Residential Energy Performance Certificate across Milton Keynes (MK Postcodes) and Northamptonshire (NN Postcodes). An EPC is a legal requirement for any domestic property that is sold or rented in the UK and Bluewire Hub are perfectly placed to provide you with your Energy Performance Certificate.

Need a Domestic Energy Performance Certificate? Then book now!



Energy Efficiency

Commercial EPC

Bluewire Hub Ltd can provide commercial landlords and letting agents with a quote for Commercial Energy Performance Certificates across Milton Keynes (MK Postcodes) and Northamptonshire (NN Postcodes). An EPC is a legal requirement for any commercial property that is sold or rented in the UK and Bluewire Hub are perfectly placed to provide you with your Energy Performance Certificate..

Need a Commercial Energy Performance Certificate? Then book now!