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The best way to heat your home which is kinder to the environment?

The best way to heat your home which is kinder to the environment?

The subject of domestic heating continues to be a popular subject. From the inevitable increase in fuel bills to the contribution of home heating on the environment. The amount of carbon emissions produced by heating systems needs to be reduced in order to meet the net-zero goal set by the Government. In fact, with 14% – 16% of greenhouse gas emissions coming from the way we heat our homes, decarbonisation of heating will play a huge part in reducing carbon emissions and hitting those targets. So, how do you heat your home which is kinder to the environment?

To help identify the more environmentally domestic heating systems we looked at the carbon emission rates of common heating systems which are specified in new builds. We ran both SAP 2012 and SAP 10 calculations to identify the best and worst as well as what the impact of the soon-to-be-released SAP 10 has on the results.

What does SAP mean?

If you are not familiar with SAP, let us provide a brief explanation first. SAP was published in 1993, and it stands for Standard Assessment Procedure. This is a calculation methodology that has been set out by the Government to calculate the energy performance of dwellings. Any dwelling developed after the 1st April 2008 must have an EPC certificate which uses the full SAP methodology and it’s also a requirement of the Building Regulations for new builds.

SAP calculations are used to:

  • Help determine energy related running costs
  • Are used for producing Energy Performance Certificates (EPC)
  • Show compliance with Part L of the Building Regulations

Why are SAP calculations important?

Without gaining a pass on SAP calculations, a property can‘t be sold or rented. In fact, building control will not provide final sign-off on any development if it doesn‘t pass which costs time and money.

Additionally, EPC certificates (rated A to G) are required for both new builds and extensions or conversions, SAP calculations are needed to produce them. If the EPC rating comes back rated equal to or lower than F, it is then illegal to rent out the property.

What is the difference between SAP 2012 and SAP 10 for home heating?

SAP 2012 was criticised for not accurately representing energy use in domestic dwellings. The calculations are based on different standard heating patterns attributed to weekdays and weekends which don’t correlate to real life use.

SAP 10 is an update to the existing SAP calculation methodology (SAP 2012). SAP 10.2 will be adopted for Building Regulation purposes in England from June this year. This follows several delays and iterations to fine tune it.

Big changes include:

  • The reduction of the CO2 emission factor of electricity by over a half
  • The carbon footprint of electric heating (over gas) will be favourable and will make it easier to achieve compliance using electric heating such as heat pumps, panel radiators and electric underfloor heating.
  • The changes to SAP 10 calculations reflect the increased use of green energy within the energy grid produced by renewable technologies such as wind farms.

Measuring the CO2 emission factors of domestic heating systems

We ran the SAP 2012 and SAP 10 calculations for a typical detached house to compare the Dwelling Carbon Dioxide Emission Rate (DER) and Target Carbon Dioxide Emission Rate (TER). These ratings determine whether a new dwelling passes or fails on its carbon emission targets set within Part L of the Building Regulations.

The domestic heating systems we compared:

  • Gas Boiler & Wet Underfloor Heating
  • Regular Gas Boiler
  • Combi Boiler
  • Electric Panel Heaters
  • Electric Underfloor Heating
  • Electric Storage Heaters
  • Air Source Heat Pump

About the property:

Type of property:        Detached House

Floor area:                  236.9m2

Low insulation:            Values you would expect to see from a house from the 1940s-1960s

High insulation:           Values you would see in a typical new build

The results


Fig. 1: SAP 2012 & SAP 10 Dwelling Carbon Dioxide Emission Rate (DER) for a LOW insulated detached dwelling


Fig 2: SAP 2012 & SAP 10 Dwelling Carbon Dioxide Emission Rate (DER) for a HIGH insulated detached dwelling


Fig. 3: Raw data which includes additional Target Carbon Dioxide Emission Rate (TER) results

What it told us using SAP 2012

  • Under SAP 2012, gas-based systems demonstrate much lower Dwelling Carbon Dioxide Emission Rates (DER) and suggests that these systems are less harmful to the environment. However, SAP 2012 uses outdated CO2 emission factors and doesn’t take into consideration the increase in use of an increase use of renewable energy technologies.
  • Looking at the low insulated dwelling results, gas does not meet the Target Carbon Dioxide Emission Rate (TER) which will result in additional measures needed such as insulation improvements to pass.
  • Using SAP 2012 air source heat pumps are a favourable source of heating when a dwelling has a high level of insulation.

What it means for SAP 10

  • Under SAP 10 it completely changes. SAP 10 takes into consideration the increased use of green energy. This makes electric heating come out on top and gas becomes heavily penalised.
  • SAP 10 makes achieving compliance easier with electric heating because electricity becomes the most environmentally friendly heating method for EPC ratings as well as the best performing.
  • For highly insulated dwellings such as the level found in new builds, electric panel heaters and electric underfloor heating rise to 2nd and 3rd respectively, the DER figure exceeds the TER benchmark which makes it easier for electric heating systems to pass without additional improvements to the building specification.

The future of domestic heating systems

The proposed SAP 10 calculations will change the way heating systems are designed for residential developments to help to comply more easily with Building Regulations. This could mean that developers will lean towards air or ground source heat pumps which helps to explain, in part, their rise in popularity when specifying heating systems for new build projects. Electric panel heaters and/or electric underfloor heating used as a primary heat source are expected to boom too as a result of the changes to the new SAP calculations. High demand electric systems may require 3 phase systems and or the likes of solar PV to be considered as part of the heating specification, especially when considering electric boilers and more integrated electric systems for large properties.

For retailers who sell heating systems they would see an increase in demand for electric heating as industry adapts to modernising the way new homes are heated to help reduce CO2 emissions.

Construction methods will also be influenced. This could include an increase in more modular offsite construction such as bathroom pods, which lends itself to electric underfloor heating because it can be easily installed offsite and simply ‘plugged in‘ when onsite.

The construction industry will adapt and heating technology will continue to be developed to be much more sympathetic to the environment. For now, and to answer the question as to what is the best way to heat your home which is kinder to the environment? electric systems are starting to become a no-brainer.

Should you decide that you would like to add some electric heating into the mix, our team are always on stand-by to help walk you through the options available to you. Simply, get in touch.


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