The age of a property is often indicative of the energy performance. Older properties were built back when building regulations were slacker and energy efficiency largely ignored or not understood, but the EPC software is based purely on figures that are entered and some defaults which must be assumed. So why do older properties still get lower ratings, despite having been refurbished?

Why are old properties inefficient?

Older properties built prior to 1930 will have solid brick walls, which offer poor insulation performance. Unless they have been retrofitted, they will have no insulation in the roof or floors. Period properties will have sash windows which are expensive to upgrade and are often in a state of disrepair.

Can you get a good rating on an older building?

Older buildings can get good EPC ratings, but it is important to remember that old buildings will have certain in-built defaults in the EPC software which will limit the final rating in many cases. To get the very best ratings, you will need to have plenty of documentary evidence to overturn these defaults and get the rating to move up into the top rating categories.

Are new builds always efficient?

New-build or recently constructed properties should be very efficient. The regulations governing the efficiency of modern buildings are very tight, and your property should have thick, high performing levels of insulation along with efficient heating, high performance glazing and potentially some renewable energy generation.

You should be aware, however, that the EPC issued when the building was constructed is always going to be higher than any follow up EPC carried out for whatever purpose. This is because new build EPCs are slightly different and go into more detail than an existing building EPC, and this means various defaults must be assumed that bring the rating down somewhat. You should still get a decent rating well above the UK average of 60 however.

What are the assumptions for EPC age bands?

If your property has inaccessible parts of the building then a default will have to be assumed. So, if you have an old loft conversion dating from the 1960s, then the software will assume that the insulation is equivalent to whatever the building regs were in the 1960s for roof room insulation.

For two of the most important types of insulation, the following is assumed by the software if no measurement or evidence of insulation can be found:

  • Up to 1966 – No insulation in the cavity or loft
  • Up to the late 1970s – A small amount of insulation is assumed in the loft, nothing in the cavity
  • 1980s – Partial cavity insulation is assumed along with some loft insulation.
  • 1990s – Cavities are assumed to be insulated on construction.
  • 2000s – There are several bands of ages post 2000. Insulation is always assumed but the u-value (performance level) of this insulation gradually improves up to today’s regulations.

You should also note that extensions and loft conversions, where dateable, will be considered separately by the software, so it is possible that the main dwelling has poor thermal performance whilst the extension is very good. The performance is weighted relative to the sizes of the extensions and the main building, producing a combined figure for the final rating.

So bear in mind that the rating you get on your EPC will be affected by the age of the building, and if you do have an older property that has been improved over the years, keep any documentary evidence of this handy for the assessor.