Energy efficiency of buildings

[edit] Introduction

Energy efficiency is the utilisation of less energy to provide the same service.

Increasing energy efficiency not only allows individuals and organisations to reduce their capital and operational costs, is can also help lower fuel consumption and so reduce the emission of greenhouse gases and help prevent climate change.

There are a great number of ways in which energy efficiency can be improved:

• Developing more efficient products and processes.
• Taking into account the entire life-cycle of products and processes, including disposal.
• Developing controls and systems to increase efficiency beyond that available from individual technologies.
• Auditing energy use and providing recommendations on more efficient technologies and practices.
• Improving the operation and maintenance of transportation, buildings, and industrial equipment.
• Retrofitting or replacing energy-inefficient technologies.
• Educating people to be more energy efficient.
• Developing policy to encourage the adoption of efficient technologies.

[edit] The built environment

The Climate Change Act was introduced in the UK in 2008, creating a long-term, legally-binding framework for tackling climate change. It set a target of reducing carbon emissions by 80% compared to 1990 levels by 2050, with a reduction of at least 34% by 2020.

The built environment accounts for 45% of total UK carbon emissions (27% from domestic buildings and 18% from non-domestic). For this reason, the built environment is a key part of the UK’s drive for energy efficiency.

[edit] New buildings

The building regulations set minimum standards for the performance of buildings, with Part L specifically regulating the conservation of fuel and power. The building regulations are increasingly strict, with a long-term goal under the Energy Performance of Buildings Directive to move towards ‘nearly zero energy buildings’.

Key criterion described in Approved Document L include:

• The designed carbon emission rate must not exceed the Target Emission Rate (TER) for a notional building of similar type, size and shape.
• Fixed building services should achieve a reasonable standard of energy efficiency. This is intended to prevent inappropriate trade-offs between different elements of the building. Minimum limiting parameters are set for key components of the building fabric to ensure that this is the case.
• Solar gains should be limited.
• Air-permeability testing and appropriate commissioning of building services systems.
• Provision should be made for energy efficient operation by providing the building owner with information enabling them to operate the building in a way that uses no more fuel and power than is reasonable.

Higher standards can be achieved through schemes such as BREEAM, Passivhaus, the Code for Sustainable Homes, Leadership in Energy and Environmental Design (LEED) and so on.

However, there is significant evidence to suggest that buildings do not perform as well when they are completed as was anticipated when they were being designed. The difference between anticipated and actual performance is known as the performance gap. Findings from studies over the last 20 years have revealed that actual energy consumption in buildings is often twice as much as predicted and can be up to 5 times higher than calculations carried out for building regulations compliance.

[edit] Existing buildings

It is expected that almost 90% of the existing building stock in the UK will still be in use in 2050, and so there is considerable focus on what can be done to improve the energy efficiency of existing buildings:

• Reducing the temperature of heating systems.
• Ensuring that air conditioning is only used when needed.
• Ensuring that windows and doors are fitted with appropriate draught excluders.
• Ensuring that thermostats are set in the correct location and used correctly.
• Fitting doors with self-closing mechanisms to minimise the time that they are open.
• Ensuring building services are operated correctly, monitored continuously and regularly serviced.
• Ensuring equipment is operated correctly and regularly serviced.
• Switching off lights when rooms are not in use.
• Keeping windows clean to maximise natural daylighting.
• Using light reflective paint to maximise natural daylighting.
• Turning off equipment when it is not in use.
• Installing of cavity wall insulation or solid wall insulation.
• Installing loft insulation.
• Ensuring new appliances are the most energy efficient available.

In 2015, the government commissioned Dr Peter Bonfield to undertake an independent review of consumer advice, protection, standards and enforcement for UK home energy efficiency and renewable energy measures. The review is anticipated to be published in March 2016.

[edit] ESOS: Energy Savings Opportunity Scheme

The ESOS Regulations 2014 implement Article 8 of the EU Energy Efficiency Directive and they require that all large businesses in the UK undertake detailed assessments of energy use and energy efficiency opportunities at least once every four years.

[edit] Energy performance certificates

The Energy Performance of Buildings (England and Wales) Regulations 2012 require that energy performance certificates (EPC's) are produced for certain dwellings and non dwellings. EPC's set out the energy efficiency rating of buildings. They are required when buildings are built, sold or rented, if they have a roof and walls and use energy to condition an indoor climate.

[edit] Information sources

• The Energy Saving Trust assist people in saving energy through the provision of advice, undertaking research and through close working with the govenment and other organisations.
• The Department of Energy and Climate Change have published a guidance document aimed at small and medium enterprises in relation to helping them become more energy efficient.
• The Planning Portal has various sources of information on Energy Saving and links to potential grants available to help offset the costs of energy efficiency measures.

[edit] Other definitions

The Energy White Paper, Powering our Net Zero Future (CP 337), published in December 2020 by HM Government, defines energy efficiency as: ‘When something performs better using the same amount of energy, or delivers the same performance for less. The principle of energy efficiency can be applied to many things: buildings, products, appliances, manufacturing processes, to name a few.'

Global Warming of 1.5 ºC, Glossary, published by the Intergovernmental Panel on Climate Change (IPCC) in 2018, defines energy efficiency as: ‘The ratio of output or useful energy or energy services or other useful physical outputs obtained from a system, conversion process, transmission or storage activity to the input of energy (measured as kWh kWh^-1, tonnes kWh^-1 or any other physical measure of useful output like tonne-km transported). Energy efficiency is often described by energy intensity. In economics, energy intensity describes the ratio of economic output to energy input. Most commonly energy efficiency is measured as input energy over a physical or economic unit, i.e., kWh USD^-1 (energy intensity), kWh tonne^-1. For buildings, it is often measured as kWh m^-2, and for vehicles as km liter^-1 or liter km^-1. Very often in policy ‘energy efficiency’ is intended as the measures to reduce energy demand through technological options such as insulating buildings, more efficient appliances, efficient lighting, efficient vehicles, etc.’

[edit] Related articles on Designing Buildings

• Approved document L.
• BREEAM.
• BSRIA publishes Artificial Intelligence in Buildings white paper.
• Building Regulations.
• Climate change act.
• Energy performance certificates.
• Energy Savings Opportunity Scheme.
• Leadership in Energy and Environmental Design (LEED).
• New energy retrofit concept: ‘renovation trains’ for mass housing.
• Passivhaus.
• Performance gap.
• Renovation v refurbishment v retrofit.
• The code for sustainable homes.

[edit] External references

• Bonfield review.
• Energy Saving Trust.
• ESOS Regulations 2014.
• EU Energy Efficiency Directive.
• Part L (Conservation of fuel and power).
• Planning Portal – Energy Saving.
• SME Guide to Energy Efficiency.