In principal, an assessor calls at the survey house and after introductions goes on to:

• Explain the purpose of the assessment and what is involved.
• Request information which may offer evidence of higher levels of heat conservation than may be normal for the age of the property (insulation certificates, receipts, boiler details, etc).

The assessor then carries out a survey, which involves taking measurements and collecting information that:

• enable the heat loss areas of the building to be determined (loft or roof/walls/windows and floor)
• relates to the thermal fabric of the building (this includes type and thickness of insulation and glazing details)
• relates to the natural and forced ventilation of the building
• relates to the hot water and heating system(s) including controls in the building
• determines the type(s) of fuel and energy sources used
• assesses the extent of low energy lighting in the building
• determines what extent of alternative energy systems and sources supplement the fossil fuels used

The data is processed using approved software and is used to produce a certificate and recommendations which is given to the client.