The most important factor in determining your EPC rating is the way the property is constructed, insulated and ventilated. The EPC assessor will be looking at the following factors.

• The construction methods and materials used in the property
• What insulation and mechanical ventilation is present?
• The volume of the property
• The dimensions of any heat loss (external) walls
• What is above and below the property?
• The location of the property (urban, suburban or rural)

The second most important factor in determining your EPC rating is the space heating systems. The EPC assessor will be looking at the following factors.

• What is the main space heating system present?
• What control systems are installed (time, temperature, zone control etc.)?
• Is there a secondary heating appliance (fireplace, gas fire etc.)?
• What control systems are present on the secondary heating?

The third most important factor in determining your EPC rating is the water heating system. The EPC assessor will be looking at the following factors.

• How is your water heated?
• How is the hot water cylinder insulated?
• Does the hot water cylinder have a thermostat?
• Is there a solar water heater installed?

The fourth most important factor in determining your EPC rating is the fixed lighting.

The EPC assessor will be looking to see what proportion of your light bulbs are low energy. It should be noted that compared to the previous three factors the lighting makes relatively little difference to your EPC rating. It is not advised to change all your bulbs over to low energy for the EPC survey, but rather to replace incandescent bulbs with low energy ones as the incandescent bulbs fail.