The Built Environment
The domestic sector accounts for 28% of total British energy demand (Department of Energy and Climate Change [DECC], 2009). It is responsible for approximately 30% of Britain’s total emissions (Department for the Environment, Farming and Rural Affairs [Defra], 2001; DTI, 2003; Power, 2008). Over half of domestic carbon emissions are from space heating (53% in 2005), while one fifth comes from heating water. The remainder comprises of appliances (16%), lighting (6%) and cooking (5%) (Department of Communities and Local Government [DCLG], 2007a). Non-domestic buildings account for 25% of the country’s carbon emissions. Non-domestic buildings emit over 100 million tonnes (Mt) of CO2 per year.
The total embodied carbon of construction materials for domestic and non-domestic buildings added up to approximately 70 million tonnes of CO2 in 2003: 13% of the total UK reported carbon emissions (Lazarus, 2005).
Under the Strategy for Sustainable Construction, new domestic buildings and schools in the UK have to be “zero carbon” in use from 2016. Public buildings must comply by 2018 and other non-domestic buildings by 2019. There is a range of legislation governing the construction industry covering issues such as sustainability, energy efficiency and carbon emissions. The key statutory and voluntary legislation is as follows:
The Code for Sustainable Homes;
Part L of the Building Regulations;
Standard Assessment Procedure (SAP);
Merton Rule; and
Energy Performance Certificates.
By making thermal comfort the goal rather than focusing on heating a building to a certain temperature, there are many options for decreasing energy demand.
The four key ways to decrease space heating demand are to:
- Improve the insulation or fabric of buildings;
- Decrease draughts;
- Decrease the heat demand through:
- Good ‘passive’ design to increase natural heat gains,
- Decrease area requiring heat,
- Decrease the thermostat/air temperature,
- Thermal comfort can be maintained through good design resulting in warmer surfaces and less drafts.
- Improving the efficiency of heating technology.
The target for domestic houses should be a 70% reduction in space heating energy demand as a whole with variation depending on building type.
In Britain in 2005 there were over 9 million un-insulated cavity walls and 6.3 million lofts with little or no insulation (DCLG, 2007b). The priority for refurbishment is clear: a demand reduction for space heating while maintaining thermal comfort. This can be achieved through design and energy efficiency measures, most notably an increase in insulation. These standards should be written into a Code for Sustainable High-Performance Refurbishment. A “whole house” approach is necessary. This means designing a strategy for the house rather than seeking incremental reactive improvement.
The embodied energy of a material or product refers to the total primary energy consumed during the resource extraction, transportation, manufacturing and fabrication of that item (Hammond & Jones, 2008). It is a measure of the quantity of non-renewable energy per unit of material. While current practice often focuses on energy “in use”, material selection should take into account the embodied energy of materials in determining preferred choice.
Natural materials such as wood and straw absorb CO2 from the atmosphere. This stored carbon could be locked away in building materials resulting in a carbon saving i.e. a “net negative”. Therefore the mass sustainable refurbishment of current buildings can also act as a carbon store. The materials used for this carbon sequestration include grown and recycled materials. This one process has three benefits: it saves carbon; it reduces the cost; and it locks carbon in the building.
The largest decrease in emissions from building stock will come from refurbishment. A Code for Sustainable High-Performance Refurbishment is required to ensure this is done to a high level and avoid it being done twice. This should include the use of natural materials were possible to lock away carbon.
Building codes for both domestic and non-domestic buildings should provide a clear definition of “zero carbon”, and include a consideration of the energy, emissions and sequestration potential of construction. A clear framework for building design should be drawn up, allowing for different routes to zero carbon buildings.
A further step for such codes would be to incorporate them into European legislation to create a set of European Sustainability Standards. This would help develop consistency in the “green industry”. It can be developed with consideration of the local environment and changes in climate throughout Europe. This standard could be based on an energy demand per m2 or per building.
Enforcement of regulations, codes and standards is crucial (Grigg, 2004). Legislative backing could take the form of sustainability or low carbon inspectors. Inspection would be without prior warning; with legal responsibility devolving upon the organisation’s directors.
Substantial education is needed to ensure that people appreciate not only the benefits of low carbon homes, but also the ways in which their own choices and actions can influence the effectiveness of the end result (Osami & O’Reilly, 2009). Action can be achieved through education, marketing and legislation.
Department for Communities and Local Government (DCLG) (2007a) Building a Greener Future: policy statement, July 2007, Wetherby: Communities and Local Government Publications.
DCLG (2007b) English House Condition Survey 2005, Annual Report: decent homes and decent places, Wetherby: Communities and Local Government Publications.
Department for the Environment, Farming and Rural Affairs (Defra) (2001) Digest of Environmental Statistics, London: Her Majesty’s Stationery Office (HMSO).
Department of Energy and Climate Change (DECC) (2009) Digest of United Kingdom Energy Statistics 2009, London: The Stationery Office (TSO).
Department of Trade and Industry (DTI) (2003) Energy white paper: our energy future – creating a low carbon economy, Norwich: TSO.
Grigg, P. (2004) Assessment of energy efficiency impact of Building Regulations compliance, report for the Energy Savings Trust and Energy Efficiency Partnership for Homes, Client Report No 219683, 10 November 2004, Watford: Building Research Establishment.
Hammond, G. & C. Jones (2008) “Inventory of Carbon and Energy”, Version 1.6a, Sustainable Research Team, Department of Mechanical Engineering, University of Bath, UK.
Lazarus, N. (2005) “Potential for reducing the environmental impact of construction materials”, commissioned by Bioregional Development Group, January 2005. Available at: http://www.bioregional.com/files/publications/Z-squaredImpactMaterials_Jan05.pdf [Live: March 2010].
Osami, M. & A. O’Reilly (2009) “Feasibility of zero carbon homes in England by 2016: A house builder’s perspective”, Building & Environment, 44(9), pp. 1917–1924.
Power, A. (2008) “Does demolition or refurbishment of old and inefficient homes help to increase our environmental, social and economic viability?”, Energy Policy, 36(12), pp. 4487-4501.