Energy efficiency is as easy as 1,2,3

Elmhurst welcomes the calls for a green recovery, with a much needed focus in making all our homes and buildings more energy efficient which is something we have advocated for over 25 years.

Elmhurst's Technical and Operations Director, Stuart Fairlie, comments: "It is fantastic to see many people including all sides of the political sphere advocating for the necessary steps to improve the energy efficiency of the UKs building stock. We also read with great interest some of the observations put forward by people about the Energy Performance Certificate (EPC), which is one of the 'outputs' of an energy assessment of a building. The main issue is that when people talk about ‘energy efficiency’ they have different metric(s) by which they measure success, which could be one, or more, of the following; less carbon, less energy or lower fuel bills.

The good news is that the national calculation methodologies, used to assess buildings can cope with all of these requirements. The issue is that by focusing only on the EPC, and its use of standard occupancy, times and temperatures can be misinterpreted. This is because the EPC was devised to allow potential purchasers or tenants the ability to compare the cost of running dissimilar homes.”

The Solution:

Elmhurst suggest that we build upon what we have and use what works well.

  1. Asset – as presented on an EPC, is a measurement of the home, the fabric, and all the heating, hot water, lighting and controls within the property, and uses a standardised heating temps and times to produce an average rating. This is perfect for people to look at a home (to buy or rent) and compare it to others.
  2. Occupation this assessment builds upon the asset calculation, but this time takes the occupiers themselves into consideration and models the prediction using their temps, running times (or previous bills). This is then not an average prediction, but a prediction tailoured to the current or intended occupants. This is perfect for owner occupiers, or any potential tenant/occupier who want to see a refined prediction based on the home (asset) and their intended use in it.
  3. Meter this takes the used (metered) energy and tells the occupants what they have used in the asset over time. This is perfect for the present occupiers to see if they are using the property in an energy efficient manner, or not. This can also be used for analysis purpose to see if the asset is not performing as expected and, by comparing it with the Occupant Assessment, we can begin to measure the performance gap.

All 3 are fantastic assessments and serve their intended purpose. The trouble is that for the vast majority of people they only see the asset rating (EPC) and criticise it for what it doesn’t produce e.g. this is not my fuel bill?

Similarly if we only concentrate on metered data, when the occupier asks what can be done to the fabric or the heating system, it wouldn’t know the answer in isolation, as it knows nothing about the asset. These are misunderstandings which needs to be overcome.

The UK is very lucky in that we have approved methodologies for the asset and the occupation, we are also working with Government on a Smeters project to reuse the metered data to help make good decisions within the asset.

Stuart continues “The three parts of this conundrum are all ready to be used, and from this data, the people can make really good choices on what they want their home or building to do. If we use all three we can model the asset, we can then model the people within it, and can predict how much energy they will consume, with metered data we can keep a track of failures/successes.

For too many years people have misunderstood, and therefore, criticised the base methodology of the asset, we need to advocate and suggest that we need all three models. Bring them all together, and with this we can really manage homes effectively. ‘One’ on its own is good, but all ‘three’ must be used in the future.”

Further similar reading:

Elmhurst have long advocated for a new look EPC:

Article published: 18/06/2020

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