Wind Turbine

At the time of writing, the methodology for EPC assessments of existing dwellings is RdSAP 10. A significant methodology overhaul from RdSAP to the Home Energy Model (HEM) is proposed for 2027. In addition, government consulations indicate future changes to the format of EPCs and minimum rating levels required for private rental properties. Methods for improving EPC ratings will therefore change in the future.

✔ A wind turbine recommendation only appears for houses and bungalows

✔ Normally only worthwhile in rural locations

✔ Terrain type has a major influence on the EPC improvement

✔ Larger turbines give substantially greater EPC improvements

✔ Documentary evidence allows exact turbine details to be entered

Wind turbines convert the kinetic energy of wind into electricity which can then be consumed within a property.

This reduces the amount of electricity the property draws from the National Grid, and if the quantity of power generated is sufficient, it can even be exported back, or used to charge a home battery.

The presence of a wind turbine can also increase your EPC rating when recorded in an assessment.

Unfortunately, wind turbines are often seen as a comical option by the general public when presented as an improvement measure on EPCs.

That's a shame because as a form of energy generation wind power has significant advantages:

• Wind energy is available night and day, compared to solar which is only available during the day.

• Wind energy is also available significantly during the winter, at a time when solar is much reduced.

Use of both Wind and Solar technologies together though help balance the level of 'green' energy generation that's possible.

In fact over the last few years wind energy has quickly become a significant contributor to GB national electricity generation. Take a look at the GB Energy Dashboard to see the significant proportion of Great Britain's electricity consumption which is now generated by wind power (Choose the 'Historical' view):

https://www.energydashboard.co.uk/historical

This was a very good week for wind in January 2026 - Wind generation is represented by the turquise colour band, solar by orange and biomass by brown. Gas is shown in blue.

I hope this might make you think again about wind turbines.

Compare this with a similar week in January 2011:

Back in 2011, which wasn't really that long ago, almost all of our electricity was generated by burning coal (brown) and gas (blue).

Wind and solar generation hardly appear on the graph at all.

This demonstrates how far we have come as a country over the last 15 years in using 'green' generation sources of grid electricity such as wind.

In general, the power generated by a wind turbine is related to:

• The square of the diameter of the rotor
• The height above ground (or roof ridge level)
• The wind speed (related to geographical location) 

As power generated is broadly related to the swept area of the rotor, if you double the diameter of the rotor then you roughly quadruple (i.e. x4) the power generated.

Also, the higher you can get the rotor above the ground, or above the ridgeline of a property, then the more power you will generate.

Lastly, the location of the wind turbine is also important. There will be some specific locations in the UK where more than the average amount of wind is experienced, but a more general guide is the quantity of housing in the surrounding area which limits the wind energy available.

In EPC assessments, the density of nearby buildings is recorded as 'Terrain Type'. The options available are:

• Urban
• Suburban
• Rural

Urban would be described as a dense urban area such as in city centres, where there are closely spaced buildings of four storeys or higher.

Suburban would be described as a low rise urban/sub urban area, such as town or village situations with other buildings well spaced around the subject property.

Rural would be described as open country with occasional houses and trees.

This choice has a significant effect on how much a wind turbine contributes towards increasing an EPC rating. 

A recommendation for a wind turbine will appear on an EPC if the following three conditions are all met:

• The property is a house or a bungalow
• The 'Terrain Type' of is set to 'Rural'
• No wind turbine is present currently

Recommendations also only appear if the EPC rating is improved by at least 1 SAP point (or 0.5 SAP points in the case of Lighting, Hot Water Cylinder Insulation and Draughtproofing).

If the 'Terrain Type' is described as Urban or Suburban, or the property type is a flat, maisonette or a Park Home, or a wind turbine is already present then a wind turbine will not be be listed as a recommendation on a new EPC.

In most cases where a recommendation appears for a wind turbine, the significant criteria is usually the property being located in a 'Rural' area.

If it is presented as a recommendation, the suggested EPC rating will be based on:

• One wind turbine on a mast with
• A blade diameter of 4.0m
• A hub height of 10m above the ridge of the property

If a wind turbine is present at a property, it can be recorded in an EPC assessment by an energy assessor.

If exact details of the wind turbine are known, they can be entered manually in the assessment. The following information is recorded:

• The rotor diameter
• The hub height above roof ridge level

Sight of documenatry evidence will be required to support the entry in case the EPC is audited.

If the wind turbine details are not known, default properties can be assumed, which are:

• 2m rotor diameter
• 2m hub height above the ridge line

The other key factor of course is the 'Terrain Type', which we have mentioned already.

In this section, I add a wind turbine to my house in the EPC assessment software and record the resulting EPC ratings.

My house is a 3-bed mid-terrace 1950s house for which further details can be seen on our Case Study 2 page.

These indicated results of course are only valid for my property. If you are interested in potential improvements for your property, please contact a local energy assessor who will be able to advise you about your potential ratings.

Anyhow, here we are, adding either a 'default' wind turbine, or a 4m wind turbine, and also noticing differences with Terrain Type set to either 'Suburban' or 'Rural': 

So, the 4m rotor and 10m height from ridge would give me a 7 SAP point increase in my EPC rating. This is with Terrain type set to suburban, which is correct for my location.

In contrast, if the turbine details are not known then I only have a 1 SAP point improvement in EPC rating.

The ratings are noticably better though if the Terrain Type is set to 'Rural', due to an expected higher wind speed resulting from fewer surrounding obstructions.

In a real assessment, the terrain type needs to be set correctly, but a 4m rotor at 10m above ridge line in a Rural location would have added 21 SAP points to my EPC rating. 

Any rating improvement for your property is likely to be different to this. As always, contact a local energy assessor to confirm the potential rating for your property before making any decisions.

Wind speed increases with height above the ground and decreases where there are surrounding buildings, trees and other obstructions.

The underlying SAP methodology therefore assumes lower energy production in urban environments than in open rural locations.

This is why Terrain Type has such a large influence on the EPC rating.

There is a whole list of rules, which depend on whether the wind turbine is building mounted or standalone mounted.

Certain circumstances fall within permitted development and a good place to research the rules is on the planning portal here:

https://www.planningportal.co.uk/permission/common-projects/wind-turbines/planning-permission-introduction

For increasing your EPC rating, wind turbines are suited more for properties in a rural setting. The turbine itself needs to be reasonably large in diameter and a good distance above the ridge height of the property to contribute significiantly to an EPC rating improvement.

As we can see from the results in the table above though, for the right properties this mght be a viable option.

If you have a wind turbine already, it would definitiely be beneficial to show any visiting energy assessor a copy of your installation documentation so he can enter the details of your specific turbine, rather than relying on the default properties in the assessment software.

If you're thinking of getting a wind turbine, are you confident that an energy assessor would consider your Terrain Type as Rural? This would give a better benefit in an EPC assessment.

Click here to return to our 'Improve Your EPC' main page, and see if there is another way you could improve your EPC rating.