How energy efficient is your property?
Thermal survey: your questions answered
Understanding the information
Improving energy efficiency in your property
- What should I do if my house shows a high or moderate heat loss?
- My house appears to have low heat loss, what else can I do to help the environment?
- What should I do if my business premise is poorly insulated?
About the survey
- Why did the Council undertake this aerial thermal survey?
- How was the survey carried out?
- When was the survey carried out
- Why have different colours been used to show heat loss instead of the thermal image?
- Why hasn't my house been included in the survey?
- I've installed insulation recently, why hasn't my home changed colour?
- What are the limitations with the thermal survey?
- Are there privacy issues associated with this survey?
- Can I remove my properties thermal value from the website?
- Why is the shape of my building wrong?
What is meant by High, Moderate and Low Heat Loss?
The colour on the map represents 9 different levels of heat loss from properties within Calderdale. These 9 levels have been grouped into three categories (high, moderate and low heat loss).
- High Heat Loss
The premise has high heat loss, which means a large proportion of heat from the building is escaping through the roof of you property. Money can be saved on fuel bills by making improvements on energy efficiency measures, such as cavity wall insulation, loft insulation and even simple draught proofing measures. - Moderate Heat Loss
The premise has moderate heat loss, which means some heat is escaping through the roof. You may have installed some insulation within the property, however, there are additional measures which can be taken to reduce your energy bill. For instance, you may need the insulation in your loft topping up, or re-programming your heating controls may also help reduce your energy bills. - Low Heat Loss
The premise has low heat loss, which is an indication that the building is well insulated with minimal heat loss. In some cases, the building may have been vacant during the time of the survey with no heating on, or the building may have little heating on. There may still be some improvements you can make on saving energy within your property, for instance, turning lights off when not required or reducing the temperature of the building.
What is meant by the Heat Loss Index?
The thermal data used in Calderdale's Thermal Survey has been measured from the amount of infra red being emitted by surfaces - the emissivity, which can be interpreted as the amount of heat being given out. The Heat loss index is an average emissivity value, which is calculated for each building, relative to the rest of the area surveyed, which is then translated into a colour on the map and separated into three areas (high, moderate and low heat loss). The Heat Loss index is an average value of how much heat is being lost from your building, which ranges from 0 - 254 (low to high heat loss).
The following factors can influence the readings picked up by the thermal camera:
- Building construction and materials directly affect the thermal values of a roof, as some materials are capable of absorbing more heat and / or retaining heat for longer. For example a slate roof may appear to give out less heat than a concrete tiled roof.
- Surface colour can affect the actual temperature: dark surfaces tend to absorb and retain more heat than lighter coloured ones.
- Heat sources such as flues and chimneys can increase the average temperature of a roof if they were being used to remove hot exhaust gases when the survey was carried out.
- Surface moisture and standing water on surfaces increases the values picked up by the thermal sensor, showing the roof to be warmer.
- High levels of dirt or large amounts of mould growth may give a higher reading than a clean surface, making the roof appear warmer than it is.
- The amount of heat emanating from roofs may be affected by nearby tree canopies or vegetation, as moisture contained in them will emit higher values, increasing the average temperature of a roof structure.
What should I do if my house shows a high or moderate heat loss?
It is worth checking to see that you have the recommended depth of loft insulation (270mm / 11in) and, where appropriate, cavity wall insulation. By insulating your property you can increase its thermal comfort and reduce your fuel bills by up to 30%. You may qualify for free or discounted loft and cavity wall insulation, depending on your personal circumstances and a suitability check on your property. See Calderdale Home Insulation Scheme for details.
There are also a number of other things you may be able do to save energy in the home at nil or minimal cost. For more details see: What you can do to save energy
Further information and advice, including grants for insulation, condensing boilers and renewable energy systems can be obtained from the Energy Saving Trust|
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Tenants in social rented accommodation should contact their landlord for details of any assistance they may be able to provide.
My house appears to have low heat loss, what else can I do to help the environment?
If your property has the recommended level of loft insulation (270mm / 11in) and where appropriate, cavity wall insulation, there may be a number of things you could do to save energy in the home at nil or minimal cost. There are plenty of ideas on our website to get you started. For more information see How you can help.
What should I do if my business premise is poorly insulated?
Help and support is available to business on energy saving initiatives which will contribute to reducing your energy bills.
Business Link and Carbon Trust provide practical ways in helping you to reduce your energy bill. For further information see Energy saving tips for businesses.
Why did the Council undertake this aerial thermal survey?
Calderdale Council believes that Home Energy Efficiency, Affordable Warmth and Climate Change are very serious issues. The aim of the thermal survey is to raise awareness of energy efficiency in Calderdale amongst householders and business owners and encourage property owners to have their buildings insulated, as well as being useful to identify areas of the district to target insulation works.
How was the survey carried out?
A plane with a thermal infrared camera flew over Calderdale during the three nights of the survey at an altitude of over 1,500ft to capture heat loss in Calderdale. The survey area was divided into strips of 750 meters in width. The plane followed a flight pattern over these strips and took images which overlapped with adjacent strips. This ensured that there was complete coverage of the survey area.
When was the survey carried out?
An aerial mapping firm was commissioned to undertake the survey and carried out three flights on the evening of 23rd, 25th and 28th March 2009. They needed to carry out the survey on a clear, cold night with no snow cover.
Why have different colours been used to show heat loss instead of the actual thermal images
The colour is used to represent the average heat recorded for the area of the coloured block. The actual aerial thermal image is based upon the 'greyscale' of black through to white. Subtle variations are difficult to interpret by eye. Different colours have been used to show relative heat loss and make it easier for people to understand the information.
Why hasn't my house been included in the survey?
Calderdale covers an area of 362 km2 which includes large uninhabited rural areas. The thermal survey has been undertaken on the main urban areas of Calderdale, including the larger villages within the Green Belt. The survey covered an area of 168 km2. The survey includes 98% of the housing and the vast majority of public and commercial buildings in Calderdale.
I've installed insulation recently, why hasn't my home changed colour?
The aerial thermal image survey was completed in March 2009 and therefore the survey provides a snapshot of the heat loss in Calderdale at that moment in time. If you have installed loft insulation since then, this won't be reflected in the images available. You will however benefit from this work during winter. It is hoped that this survey can be repeated some time in the future to see what differences have been made.
What are the limitations with the thermal survey?
Thermal imaging can be particularly useful, providing information which would otherwise be very difficult to obtain. However, there are some limitations to the data, which include:
- The image is simply a snapshot at one moment in time of how much heat a property was losing from the roof.
- The outcome of the survey is affected by certain factors (for instance how many people were at home on the night of the survey, whether the heating was on, the building materials used in constructing the property, level of insulation, commercial premises with residential above or vice versa).
- The method of capturing data can be contrained by steep terrain. Calderdale is very hilly in parts and therefore the results of the heat loss survey may not accurately reflect the property's heat loss in a limited number of properties in Calderdale, particularly the dwellings that are cut into very steep hills.
- During the survey, the aircraft including the sensor is subject ot variations in pitch, yaw and roll movement caused by forward inertia and cross winds during the flight. These factors can also affect the output.
Whilst any data can have limitations, Calderdale's intention in publishing the data online is to stimulate interest in the subject of home heat loss and to motivate residents and businesses to insulate their properties. We are hopeful that this will be the outcome.
Domestic development such as or changes to outbuildings / extensions are no longer surveyed by the Ordnance Survey and therefore as a general rule, are unlikely to be seen on Ordnance Survey maps.
Are there privacy issues associated with this survey?
No, thermal imagery does not shown actual images. The information collected through the survey has been converted into relative values. Colour codes have been attached to the values and have been displayed on an Ordnance Survey map base layer. The range of colours have been used to show colder (low heat loss) through to warmer buildings (high heat loss).
Can I remove my properties thermal value from the website?
Yes. If you are not happy with your property being included within this thermal survey we are able to remove your data from the online system. Please e-mail your Unique Property Reference Number (UPRN) (which can be found on your property's thermal efficiency results) and address of your property, to maps@calderdale.gov.uk and we will proceed with your request.
Why is the shape of my building wrong?
The map was made using Ordnance Survey (September 2008) information, which was the most accurate information available at the time. New buildings may not have been identified by Ordnance Survey at the time of publication as such there will be inaccuracies in a project of this scale which are unavoidable.
