EPCs

Home Energy Audit / Assessment, Retrofit Design Services, Energy Performance Certificate; which one do you really need and how do you see through the jargon?

With the amount of organisations out there offering ‘energy audits’ or ‘energy assessments’ these days, particularly since the demise of the Government’s Green Deal scheme, it can be difficult to know where to start looking if you’re a homeowner.

While we are yet to come across a service that offers the value of our own Home Energy Masterplan, we understand that people will want to research the market before engaging us. With this in mind, we’ve tried to offer a bit of general guidance as to what to look for and what questions to ask when considering your options.

Home Energy Audit / Assessment

This is a broad term which is used to describe a range of services. Most of the time the assessment or audit is based on some level of modelling or calculations. This is the very least you should expect. We have seen many reports over the years, shown to us by clients, which are based on a little modelling and a LOT of conjecture. It can be difficult to differentiate the good from the bad however as clever formatting and shiny graphics can disguise a lack of analysis. To make sure that the organisation you are talking to intend to carry out detailed modelling of your property we recommend asking a few basic questions that they should have no problem answering (if they’re offering a valuable service):

  • On which methodology is your modelling software based?
  • How are the energy, cost and CO2 savings of retrofit measures calculated?
  • Does your model take into account how the property is actually being used and how does it do this?
  • Does the model consider the cumulative impact of applying groups of measures?

Retrofit Design Service

This type of service is usually offered by Architects or contractors who will take you from start to finish through the process of either a whole house retrofit or an extension. The service should theoretically start with a detailed options assessment to make sure that no opportunities to further improve the property for a marginal cost are being missed, however this is often limited by a lack of knowledge on the part of the architect, or by the contractor having a pre-determined list of measures and materials with which they are comfortable working. This means that the only way to really know if all of your options have been carefully considered is to insist on a detailed assessment at the beginning of the project.

Parity Projects provide our Home Energy Masterplan via various partner organisations who can offer a design and build service. We also offer a full Project Management service.

Energy Performance Certificate (EPC)

An EPC is a simple benchmarking tool which gives the property an energy efficiency rating between A and G. This can be a useful guide when moving into a property as to how difficult to heat it might be. The EPC is based on a very limited set of data points however and is not designed as a decision making tool.

The table below details some specific differences between the different types of assessments.

Energy Performance Certificate (EPC) Green Deal Assessment (GDA) Home Energy Masterplan (HEM) Building Performance Specification (BPS)
House data collected About 75 data points collected during survey, building only About 75 data points collected during survey Over 350 data points collected during survey Similar to HEM data collected
Usage data collected None Actual bills used to calibrate Actual bills used to calibrate

All lighting and appliances identified and usage recorded

Similar to HEM data collected
Energy costs National averages used, updated quarterly National averages used, updated quarterly Use the clients actual tariff rates N/A
Depth of analysis Baseline only, automated output.

Limited range of measures

Automated output.

Limited range of measures

All practically feasible measures analysed, cumulative impact of measures considered All practically feasible measures analysed, cumulative impact of measures considered
Use of costs Central database and a very wide range of costs per recommendation. Central database and a very wide range of costs per recommendation. Accurate and up to date costs applied to recommendations based on recent quotes N/A
Recommendations Automated, not client specific Automated, not client specific – occupancy factors are applied to give a guide on suitability. Two types:

Individual analysis of each potential measures

Packages of measures that you choose

Product specific specifications generated based on the exact requirements of the home, your budget and your aspirations
Specification of work N/A N/A N/A Pinpoints the most suitable products to suit the techniques identified in the HEM