Doors

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 consultations indicate future changes to the format of EPCs and minimum rating levels required for private rental properties. Approaches to improving EPC ratings will therefore change in the future.

Doors are an element of 'building fabric' and therefore contribute in a small way to the overall heat loss of a property.

This in turn affects running costs and because EPC ratings are currently a cost-based metric, it affects the overall rating.

During an EPC assessment, energy assessors record the number of external doors present at the property.

Only external doors are effectively considered, or rather doors that are within heat loss walls. Internal doors within a property are not normally included. Also, the door from a flat to a heated corridor for example is not counted.

Qualifying doors that have a glazing content of 60% or more are recorded as windows in the assessment rather than doors.

It is therefore entirely possible for a property to be assessed as having no doors in the case where all doors are highly glazed or not counted.

In most cases, assessment against the 60% rule is easy to make by simply looking at a door. In cases where it is not clear, the procedure is as follows: Measure both the area of the whole door frame, and also a total of the area of glazing in the door. Divide the glazed area by the frame area and multiply by 100 and you arrive at the percentage proportion of glazing.

For each recorded door, the presence or absence of draughtproofing is also recorded.

Remember, assessments only record the presence of various elements, including doors, and no information is recorded about their condition.

Finally, an option is available to indicate that a door is 'insulated'. This requires documentary evidence of the overall u-value of the door, and this needs to be manually entered. This is very rare.

At the time of writing, the methodology for producing EPCs for existing dwellings is RDSAP 10.

This methodology assumes the area of a door is 1.85m2 in area and there is no option to alter this.

Due in part to this, a pair of French doors is counted as two doors in an assessment.

The methodology also assumes the u-value of a door as follows by default (extract from the RDSAP 10 Specification document):

Age bands vary slightly between England & Wales, Scotland and NI, but for England & Wales where I am based, these represent:

Age band M is 2022 onwards

Age band L is 2012 to 2021

Age band K is 2007 to 2011

Age bands A-J is up to 2006

From some quick research, I believe the current maximum u-value allowed for new replacement doors in existing dwellings is 1.4 W/m2K. This effectively fits in with the table above for age band M although I also believe this is better than the current new-build backstop which is 1.6.

Consider the case where you may have an older house, say a 1950s terrace house. If you have brand new replacement doors fitted today then the u-value of those doors will be 1.4 W/m2K (or better) but the methodology will assume a value of 3.0 instead.

The following recommendations are available in the methodology relating to doors:

Draught proofing of windows or doors

This recommendation is considered when:

• The existing dwelling has single glazed windows or external doors which are not draught proofed.

It is triggered if:

• The existing dwelling has less than 100% draught proofing of windows and doors.

The rating provided with the recommendation applied includes:

• 100% draught proofing

Insulated doors

This recommendation is considered when:

• The existing dwelling is
  • a house, bungalow or park home or
  • a (flat or masionette) and (no corridor or more than one door) ie door directly to outside

It is triggered if:

• Door(s) directly to outside not insulated

The rating provided with the recommendation applied includes:

• Change doors directly to outside to insulated doors with u = 1.4 W/m2K

Recommendations appear on an EPC only if they improve the rating by at least 1 SAP point, or 0.5 SAP points in the case of cylinder insulation, draught proofing and low energy lighting.

What I find interesting is the recommendation for 'Insulated doors' and the applied rating including: Changing the doors to 'insulated doors' with a u-value of 1.4.

As all new standard replacement doors fitted today will have a u-value of 1.4, if you have an older property and have a new replacement door fitted today, it should be possible to obtain documentary evidence of the u-value of that door from the installation company, declare the door as 'insulated' in a fresh EPC assessment and manually override the u-value.

This would not in itself trigger a Smart Audit, although the difference in rating it could make would be very limited.

We'll try this in an exercise next to see what difference it could make.

Text to follow showing EPC ratings with different door configurations.

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