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Zero Carbon or Energy Efficient? Which is the best target for homes?

by on May 31, 2018

For many years the objective of legislators was to ensure that new houses were “zero carbon”: i.e. that not only was the building structure very energy efficient, but that additional renewable energy technologies (such as solar PV panels) were incorporated to generate the power needed to run the house. This was always going to be difficult to achieve. Producing very energy efficient homes is perhaps a more practical goal.

Why is building energy efficient homes important?

From a UK-wide perspective, the incentive is provided by the fact that 30 per cent of the energy used by the country is used to heat and run homes.  Given the national focus on reducing energy consumption – and consequent carbon emissions – anything that can reduce that 30 per cent figure makes a great contribution.

From an individual home-owner point of view, the priority is even more obvious; a comfortable living space with minimal fuel bills.

What is the best way to increase the energy efficiency of a home?

The most effective measures to improve the energy efficiency of new housing are those which are “built in” to the structure of the property.  Industry leaders H+H call this the “fabric first” approach to building design.

This approach follows the simple logic that if the energy efficiency is built into the fabric of the home by the choice of materials and the design, then the structure will retain its energy efficiency for the lifespan of the building.

How close to zero carbon is close enough?

Building regulations set the bar for energy efficiency, setting out minimum standards for the performance of new homes.  However, these are just minimum standards and can easily be exceeded.

For those looking for higher performance standards, the Code for Sustainable Homes provides useful additional insight.  Although not mandatory and indeed no longer part of the government’s plan for improving the quality of new build, the Code is still widely recognised as a measure of both energy efficiency and sustainable development.

The Code included several levels of performance: Code Level 3 being essentially equitable to current building regulations.  Code 6 is essentially zero carbon.  Any performance above Code Level 3 is a very energy efficient home.

One of the reasons that the Code was abandoned by the government was the perceived cost and complexity of building to the higher levels of the Code.  To prove the efficiency of their product, H+H took part in a government-funded research project which proved that by using aircrete blocks, it is possible to achieve Code Level 4 without relying on renewable energy sources.

Find out more about the project.

The goal for the building industry should be to maximise the energy efficiency of the building structure.  Built to a high standard, a home made from aircrete can be designed so that no heating at all is required to maintain a constant 20 degrees Celsius (0C) temperature throughout the year, which should be the ambition of the house builder.

Download H+H’s guide on designing and building energy efficient buildings with aircrete.

This article is bought to you courtesy of our content partner H+H.


  1. The reason why houses and other buildings must be carbon negative (sometimes referred to as solar plus) is that all the other sectors; power generation, agriculture, industry/manufacturing, transport (including shipping and air) and the military will have great difficulty in getting close to 80% reductions by 2050 and zero beyond that.
    The nature of the occupancy should be considered together with the efficiency of the building. The Government and planning authorities should be encouraging ‘custom-splitting’ that would enable two (or more) households to partner in sub-dividing houses including a green refit. The custom builders would have parts of houses rather than the serviced plots promised by legislation. Older households could downsize in place. Both households would heat the space and fabric they occupy.

  2. JOHNSON permalink

    The ‘Utopia’ of carbon neutral new- build is ridiculous, surely? (please discuss?) The concept involves these properties being intrinsically ‘sealed’ to outer heat loss, involving a small amount of fan assisted air ventilation, which does its job, but does not allow enough air-flow for those who suffer from asthma and other lung /breathing problems, and also involving the extra electrical fan ventilation with that associated ‘carbon’ impact on the environment.
    There is no such thing as a ‘free lunch’ on this planet.Other classic examples are the latest energy saving and efficient gas central heating condensing boilers, which are just what they say, BUT they only last 10 years on average, whereas the older types can still be running after 25 years.So having to manufacture ongoing replacement boilers can indeed be more damaging to the environment? For every plus in life there is a minus- a balancing equation, which the Chinese
    call ‘yin and yan?’

  3. Doh- tell me something I didnt know. As”eco” architects we have been pushing fabric first for the past 10 years, withe the bells and whistles of renewable s being the elements that pushed it that bit further. However, the attitude that we make our building zero carbon is critical as we are in a terrible deficit position and need to be more than zero carbon if our planet has any chance of recovering. Thus our governments reduction of the RHI is unforgivable. It is genuinely both that is required. When we have the advent of good practical batteries for houses, we may have a real chance then.

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