Definition of a zero carbon house
A zero carbon house is one that does not increase the amount of carbon dioxide (CO2) in the atmosphere (net carbon emissions over the course of a year).
What causes carbon emissions?
Burning fossil fuels – oil, petrol, gas and coal – produces carbon dioxide. When we use fossil fuels to build houses, heat our homes or generate electricity carbon is released into the atmosphere. The increase in carbon dioxide is causing global warming, rising sea levels, extinction and more unpredictable weather patterns across the world. In order to change these patterns, we need to reduce the amount of carbon dioxide that our homes produce.
Different ways of defining zero carbon
There is some controversy over what is included within the definition of zero carbon. In 2007, the UK Government created the world-leading Code for Sustainable Homes, a set of standards to assess the complete environmental impact of new dwellings. To reach Level 6, the most exacting standard, all the energy you used in your home, whether from computers or washing machines or central heating, had to be renewable. In other words, no fossil fuels for anything at all.
Other aspects of the Code cover water usage, daylighting, site ecology, etc. Although criticised by some, the Code has also been described as “one of the finest pieces of conviction politics in a generation”.
However, in 2011 the Government sadly watered down the original definition of zero carbon homes that the industry has been working to, and for which there was broad backing. While there was still a so-called zero carbon requirement, it no longer applied to all energy used within a home. Heating, lighting, hot water and building services were measured but disappointingly built-in electrics (hobs, ovens, washing machines) and all loose electrics (computers, TVs, supplementary heaters) were all ignored.
Next, “small” housing developments were exempted, and a get-out called “allowable solutions” was introduced. Rushed through on the last day of Parliament in March 2015, the Code for Sustainable Homes was finally abolished, despite criticism from many. Even the Government’s own Environment Audit Committee urged them to reconsider as the Code “has been pushing up home building standards and creating a thriving sustainable building industry in the UK”. There was widespread criticism of the July 2015 announcement scrapping plans to make all new UK homes carbon neutral.
Carbon negative house
Technically, zero carbon house is not just carbon neutral – it’s carbon negative. Over the course of a year, the house generates more electricity than it uses, so it cuts CO2 being produced elsewhere. zero carbon house is being monitored by Lubo Jankovic, Professor of Zero Carbon Design at Birmingham School of Architecture, Birmingham City University. He has found that annual carbon emissions have reduced from 21,000 kg CO2, based on the original two-bedroom 1840 house, to -660 kg CO2.
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