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Solutions are presented in accordance with the stepped approach taken in the energy hierarchy. There are many solutions available within each step and their appropriateness and applicability will vary according the development type, nature and scale; likely building occupants; site constraints; and the technical capability of the solutions themselves.

When designing for sustainable energy management it is important that issues and opportunities are identified at the outset as part of an on-going discussion between client, architect/designer and the planning authority. Some specific points in relation to development types are provided using the link below.

The Energy Hierarchy The energy hierarchy is used to guide and prioritise the steps which should be taken to minimising energy use and reducing associated GHG emissions. These steps are sometimes shown as:

BE LEAN – take step to reduce energy consumption through improved fabric efficiency and low energy use lighting
BE CLEAN – Seek to maximise efficiency of delivery of space heating requirements, such as communal boilers or district heat networks
BE GREEN – Generate heat and electrical energy on-site and renewably to further reduce the developments carbon impact


Reducing demand and energy efficiency

This section describes many of the energy efficiency solutions that address the first steps on the energy hierarchy. The applicability of these solutions depends on the type of project; in particular, whether it is a new building or a refurbishment. Specific attention is drawn to considerations relevant to the residential, commercial, educational, health and industrial sectors.

Building design

In the case of new buildings, energy issues should be given consideration at the early stages of design (ideally at project inception) to enable the best technical and economic solutions to be achieved. These measures are influenced by decisions made throughout the design process. Passive energy saving measures typically require little or no maintenance and last throughout the lifespan of the building with no energy input. Capital cost implications of measures are variable, but in most cases, these design choices can lower building operational costs through reducing building service requirements.

At an early design stage there are many opportunities to develop an integrated approach to energy use and savings, including the determination of the physical form and characteristics of the building.

Consideration should be given to the following

  • Orientation - sun path around the site, prevailing wind direction and the need for clear views, this may determine levels of solar gain for heating and cooling implications, where possible single aspect dwellings should be avoided to prevent overheating risks.
  • Reducing the amount of exposed external area compared with enclosed internal volume
  • Incorporation of atria, courtyards or sunspaces can reduce energy consumption in deep plan buildings
  • Thermal mass should be fully considered and included or excluded as appropriate, to correspond with activity and occupancy patterns
  • Landscape design can influence the microclimate (and reduce energy demand) by providing shelter from driving rain and wind
  • The ratio of glazing to solid material in the external walls can be optimised to provide benefits from natural light and useful solar gains, whilst avoiding excessive heat losses or gains
  • Where appropriate and possible, these passive solutions should also be applied to refurbishment projects.

Air tightness

The majority of heat loss from a building historically occurred via conduction through the walls, roof, windows etc. However, Part L has improved the U-values of new buildings sufficiently such that the heat lost via air movement has become an important area to consider. Warm and cold air moves around a building through both controlled means (ventilation design) and uncontrolled means (infiltration leakage). Infiltration is generally undesirable as it disturbs the ventilation strategy and results in excess heat loss in winter.

Careful detailing of the building fabric and junctions between building elements such as windows and external walls reduces heat losses from air leakage. Targets for air leakage rates should be specified at the design stage and verified during construction through pressure testing, which gives the opportunity to address any problem areas.

Part L 2016 includes a maximum permissible air-leakage rate (for both domestic and non-domestic) of 10 cubic metres of air every hour for every square metre of internal floor area (m3/m2/hr) when tested at an internal air pressure of 50 Pascals (which is achieved using fan blowers). Mandatory testing results evidence that many buildings perform significantly better than this figure, with leakage rates of 5m3/m2/hr@50Pa or less being commonplace.
Reducing air-leakage to 3m3/m2/hr@50Pa or less might introduce the need for mechanical ventilation, to ensure there is adequate ventilation at all times of year. Provisions within Building Regulations Part F (ventilation) have been increased for dwellings with a design air permeability tighter than or equal to 5 m3/(h.m2) at 50 Pa.

Mechanical ventilation is often regarded as an energy intensive solution; however, using mechanical ventilation with heat recovery (MVHR) in a very air-tight building with relatively low cooling loads can provide a very energy efficient solution. For instance, ‘PassivHaus’ buildings in Europe have completely avoided the need and cost of a conventional heating system by being extremely efficient and installing MVHR. The increase in capital costs can be a few percentage points and it is claimed this can payback many times over within the lifespan of the building.  The trade-off is the reliance on the mechanical ventilation system for heat and ventilation throughout the year.

Thermal Bridging

With drastic recent improvement in the typical U values of materails used in modern construction, the impact of thermal bridging has become increasing important in energy efficiency and preventing problems such as condensation. Thermal bridges can now account for 20-30% of the heat loss in a typical new build home.

A thermal bridge (sometimes called a cold bridge) is a localised weakness or discontinuity in the thermal envelope of a building. They generally occur when the insulation layer is interrupted by a more conductive material, such as a structural element.

There are two types of thermal bridges in buildings - repeating and non-repeating thermal bridges.

Repeating thermal bridges occur consistently throughout the building and therefore their impact can generally be calculated and mitigated against, for example mortar in brick and block work, steel or timber frames.

Non-repeating thermal bridges are dealt with by “PSI-values” – pronounced ‘Si ’ (silent p), and designated by the Greek letter ‘ψ’. Their effects on heat loss are calculated by thermal modelling software, and they are accounted for separately in SAP calculations in addition to U-values.
The Key Junctions of any building may vary depending on its design and build type, however typical junctions to be aware of where a higher thermal bridge might compromise building performance include:

  • Window and Door frames – positioning of frame in relation to wall insulation and correct selection of insulating materials around lintels and cavity caps.
  • Ground level walls – using light weight masonry on internal cavity walls and ensuring insulation materials run below damp proof course.
  • Roof Eaves – ensure roof insulation does not curtail before reaching the eaves and where possible increase insulation depth at eaves (may require redesign of roof trusses

A good guide to reduction of thermal bridge can be found here.

Passive design and solutions

To achieve their energy efficiency benefits, passive solutions for ventilation, heating and cooling usually need to be applied in a controlled manner.
In particular, the controlled use of daylighting, natural ventilation and passive heating and cooling can create a low energy building with reduced environmental impacts, whilst still achieving comfortable conditions for occupants. The following solutions can help achieve this:

Passive solar design

Passive solar design is the capture of useful solar gains (heat) to offset heating energy requirements. Atria and sun spaces are typical examples of this approach, however solar gains will be experienced in any rooms which have a southerly facing glazed aspect. It is important to balance the advantages passive solar design with the risks of summertime overheating.

Cooling and overheating

Limiting the effects of solar gains in summer is covered by Part L – Criterion 3 of Building Regulations. SAP and SBEM calculations will include high level analysis of overheating risk to demonstrate compliance. This test does not cover all influencing factors and Part L states that designers may want to exceed the requirements to consider the impacts of future global warming on the risks of higher internal temperatures occurring more often.

The Cooling Hierarchy set out below can be applied and dynamic thermal modelling can be carried out to remove the risk of overheating.

  1. Minimising internal heat generation through energy efficient design: For example, heat distribution infrastructure within buildings should be designed to minimise pipe lengths, particularly lateral pipework in corridors of apartment blocks, and adopting pipe configurations which minimise heat loss e.g. twin pipes.
  2. Reducing the amount of heat entering the building in summer: For example, through use of carefully designed shading measures, including balconies, louvres, internal or external blinds, shutters, trees and vegetation.
  3. Use of thermal mass and high ceilings to manage the heat within the building: Increasing the amount of exposed thermal mass can help to absorb excess heat within the building using night time purge to provide a stable temperature.
  4. Passive ventilation: For example, through the use of openable windows, shallow floorplates, dual aspect units, designing in the ‘stack effect’.
  5. Mechanical ventilation: Mechanical ventilation can be used to make use of ‘free cooling’ where the outside air temperature is below that in the building during summer months. This will require a by-pass on the heat recovery system for summer mode operation.

Once these areas have been considered, if there is still a risk of overheating active cooling may be incorporated. Where this is necessary, the lowest carbon option should be selected. It should also be ensured that the system is sized to meet the cooling demand.

Atria and courtyards

Enclosed glass volume, can be used to bring daylight and natural ventilation into the centre of deep plan buildings.

Void in the middle of a building, or group of buildings, which is open to the elements. 

Natural lighting

The use of natural light rather than artificial systems can offer significant energy savings. In addition to atria and courtyards, techniques to bring light further into deep plan buildings include sun pipes and solar reflectors. These can be either included during construction or can be retrofitted. 

Natural ventilation can be used in situations where the external conditions are free from excessive noise or poor air quality and where the intended use of the space allows. In narrow plan buildings, a typical approach is to use openable windows. In larger spaces, additional measures would be required, for example the use of a ‘stack effect’ system (see earlier energy efficient design diagram). 

Optimisation of glazed areas - balancing daylight against heat gains and losses

Uncontrolled solar gains can result in overheating and glare.

The use of solar shading or solar control glazing allows diffused light into the space and keeps excessive heat gains out.

Narrow floor plates (to facilitate natural ventilation)

Narrow floor plates: opening on single side

Maximum depth of 7m for effective natural ventilation via an opening on one side of the space.

Narrow floor plates: opening on opposite sides

Maximum depth of 15m for effective natural ventilation via openings on opposite sides of the space.

Thermal mass

Materials such as concrete, brick and stone absorb heat, can help prevent a building from overheating.

Stored heat is released later when required. 

Passivhaus Standard

Passivhaus buildings provide a high level of occupant comfort while using very little energy for heating and cooling. Passivhaus buildings achieve a 75% reduction in space heating requirements, compared to standard practice for UK new build, it therefore gives a pathway to achieving the 80% carbon reductions that are set in the UK for 2050.Passivhaus also applies to retrofit projects, achieving similar savings in space heating requirements. The standard is achieved through:

  • Excellent levels of insulation with minimal thermal bridges
  • Passive solar gains and internal heat sources
  • Excellent level of airtightness
  • Good indoor air quality, provided by a whole house mechanical ventilation system with highly efficient heat recovery
  • Quieter indoor space
  • Greater building fabric durability
  • Better use of available floor space

Building services or active solutions

Building services equipment, such as boilers, air handling units and lighting systems use energy to provide comfortable internal conditions for building occupants. Where it has been determined that mechanical services are required to provide comfortable internal conditions, efficient plant should always be specified.

Minimum boiler efficiencies are recommended in the compliance guideline documents that accompany Part L: the ‘Domestic Building Services Compliance Guide’ and the ‘Non-Domestic Building Services Compliance Guide’.  Both of which are available for download from the Planning Portal.

It should be remembered that the recommendations in these documents are for the minimum acceptable performance and should be bettered where possible. For instance, boilers with an operating efficiency of over 90% are readily available at no or minimal additional cost. The official boiler efficiency database is available on the Building Energy Performance Assessment website.

For refurbishment projects, the opportunity to upgrade building services with the most efficient replacements should always be assessed, particularly as making replacements during the refurbishment will almost always be more cost-effective than returning in future years. ‘Easy wins’ that pay back in a short timeframe, such as additional insulation to existing pipes and ducts or the upgrade of lighting ballasts, should not be overlooked in favour of ‘big ticket items’ such as new boilers or renewable energy.  Note that if significant changes to the building fabric performance and ventilation is being made, existing building services may well be oversized for the refurbished building and therefore upgrades/replacement systems may well be smaller than before.

If mechanical ventilation is being used then energy efficient fans should be specified. The building services compliance guides (referenced above) contain minimum performance values for Specific Fan Power, which should be bettered where possible. In air-tight buildings, the use of heat recovery should be investigated, in the form of plate heat exchangers, thermal wheels, or run-around coils, depending on the space availability and ventilation requirements. Note that using heat recovery in buildings that are not air-tight can lead to reduced efficiency of heat recovery systems and in some cases an increase in energy consumption. Ideally the building services designer would model the fan and seasonal energy consumption under several realistic scenarios. Plate heat exchangers

Air (or water) moving in opposite directions is separated by thin sheets of metal, which allow heat transfer. In this way, heat can be recovered from the exhaust air and used to pre-heat incoming air.

The use of air conditioning and comfort cooling should be restricted to those areas where it is strictly necessary. Artificial lighting systems for use internally and externally should be as energy efficient as possible. Low energy light bulbs are widely available and use only 20% of the energy of standard bulbs, and can therefore offer significant energy and maintenance/replacement savings.

For refurbishment projects, services should be upgraded wherever possible. If costs are prohibitive, then more economic measures could be implemented, such as insulation of pipes and ductwork.

Plate heat exchangers

Air (or water) moving in opposite directions is separated by thin sheets of metal, which allow heat transfer. In this way, heat can be recovered from the exhaust air and used to pre-heat incoming air.

The use of air conditioning and comfort cooling should be restricted to those areas where it is strictly necessary. Artificial lighting systems for use internally and externally should be as energy efficient as possible. Low energy light bulbs are widely available and use only 20% of the energy of standard bulbs, and can therefore offer significant energy and maintenance/replacement savings.

For refurbishment projects, services should be upgraded wherever possible. If costs are prohibitive, then more economic measures could be implemented, such as insulation of pipes and ductwork.

Building management systems/controls

The use of an appropriate control system can significantly reduce energy wastage. For example, sensors can be used to detect when there is sufficient daylight in a space and can dim or switch off the artificial lights in response.
Variable speed controls on pumps and fans can save a significant amount of energy. This allows building services to use only the energy that is required, rather than continuously operating at full capacity.

A BMS (Building Management System) is a sophisticated network of sensors and controls for the building services. A BMS can be programmed for optimum operation and minimal energy use. BMA are typically installed on larger projects.

Use of a BMS facilitates energy monitoring and can highlight areas of excessive use where savings could be made. In smaller buildings, a simpler approach could be to take regular readings of utility meters and any sub-meters. However, a benefit of having a BMS is that it frees up time that might otherwise be spent taking meter readings, so more time can allocated to the analysis of the data and to developing a plan for making improvements.
Many of these systems can be retrofitted, although this is not a reason to exclude them at the design and construction stage.

Consideration should be given to the maintenance implications of installing controls and sensors. In a few instances, the additional maintenance and replacement costs associated with e.g. additional sensors and motorised controls (such as daylight controlled blinds) can be greater than the cost savings arising from reduced energy consumption.

Refurbishment projects

For refurbishment projects, a building survey will identify services that are underperforming or nearing the end of their life cycle. The opportunity to upgrade them with the most efficient replacements should always be assessed, particularly as making replacements during the refurbishment will almost always be more cost-effective than returning in future years. ‘Easy wins’ that pay back in a short timeframe should not be overlooked in favour of ‘big ticket items’ such as new boilers, windows or renewable energy.


Easy wins

  • Draught proofing of windows, doors and service penetrations
  • insulation to hot or chilled water pipework
  • extra lagging to any hot water storage vessels
  • sealing of ductwork leakage
  • replacement of AC pumps and fans with variable speed DC/EC motors
  • upgrade of burners in an existing boiler
  • upgrade of light fittings (might also require new ballasts)

Renewable and low carbon energy solutions

The use of cost-effective renewable or low carbon (RLC) energy sources reduces the use of conventional energy and associated greenhouse gas emissions.

The suitability of RLC technologies varies from project to project and is dependent on site factors, location and funding availability.
 You will need to consider a number of questions when deciding which solution(s), if any, are most suitable:

  • Is it right for this location and this type of building
  • Will it meet the energy needs of the occupier AND reduce CO2 emissions?
  • Who will be responsible for maintenance and management?
  • How difficult will it be to maintain?
  • Will it have a detrimental impact on neighbours and the wider environment/landscape?
  • Is it compatible with other design solutions being implemented?
  • What other technologies and support will be required for occupiers to use it effectively?
  • Is there enough space?
  • Does it need separate planning permission, or other permissions?
  • Does it provide scope for future energy and carbon reductions?

The Hertfordshire Renewable and Low Carbon Study provided a high level analysis of the feasibility and appropriateness of a range of RLC technology solutions across Hertfordshire, including the solutions presented below. Click here to download a copy of the RLC study.

Funding streams for RLC solutions

Increasing the use of renewable energy is important for Government to achieve its national and international targets. Various financial incentives have been recently introduced to enable renewable and low carbon solutions to compete on an economic basis with conventional fossil fuels. These include:

  • Energy efficiency grants – discounts on wall and loft insulation and better boilers and controls.  Developers and tax-paying building occupiers can gain cash flow discounts on energy efficiency products using Enhanced Capital Allowances (ECA).
  • ECO was introduced in January 2013 to reduce Britain’s energy consumption and support people living in fuel poverty by funding energy efficiency improvements in homes. The larger energy companies are set obligations to install insulation and heating measures in order to achieve reductions in energy usage and heating costs.
  • A new grant scheme has launched to help businesses in Hertfordshire reduce energy costs and greenhouse gas emissions. Low Carbon Workspaces offers eligible small and medium sized enterprises grants to cover up to a third of the cost of installing energy saving measures. 
  • Feed In Tariffs (FIT) – incentives for low carbon electricity generation from micro-technologies such as photovoltaic panels and micro-CHP.  The utility company pays the consumer for electricity generated. Click here for more information.
  • Renewable Heat Incentive (RHI) – introduced to incentivise low carbon heat generation from micro-technologies such as solar thermal, biomass boilers and ground source heat pumps. Available for domestic and non-domestic projects. Click here for more information.
  • Renewable Obligation– was tailored towards large energy installations such as wind farms and biomass power plants. The options above are more appropriate for building projects. From March 2017 the RO is being replaced by Contracts for Difference (CfD) Click here for more information.
  • Heat networks delivery support – Support and funding is available to Local Authorities and other organisations planning or implementing heat network projects. Click here for more information.

Energy Service Company’s and Energy performance Contracts – for some developments, particularly where community or district heating is involved, development can attract finance to install renewable or low carbon energy sources through Energy Service Companys (ESCo). The ESCo can provide up to 100% of capital funding in return for an extended contract to provide energy at an agreed price. In cases where multiple technologies are used Energy Performance Contracts are used to guarantee a minimum amount of energy savings. Multiple products and services are available in this area and it is recommended care is taken before entering into any service contract.
In addition to the consideration of technical and economic feasibility on projects, it is vital to address planning issues associated with the installation, including local environmental and visual impacts.

Energy Hierarchy recap
Following implementation of energy efficiency measures the next stage of the energy hierarchy is to explore clean, low carbon and decentralised forms of heat and energy. In particular options for connection to or development of District/ Community Heat Networks or decentralised energy networks should be explored, before exploring individual building based options.

District heating networks

District heating is an alternative method of supplying heat to buildings, using a network of super insulated pipes to deliver heat to multiple buildings from a central heat source. Heat is generated in an energy centre and then pumped through underground pipes to the building. Building systems are usually connected to the network via a heat exchanger (also known as a heat interface unit (HIU)), which replaces individual boilers for space heating and hot water.

Whilst there is some amount of thermal loss from the heat distribution infrastructure, the aggregation of small heat loads from individual buildings into a single large load allows the use of large scale heat technologies, including the capture of waste heat from industrial processes or power generation, or other large scale heat generation technologies which are not viable at a smaller scale. Of particular interest is combined heat and power (CHP) technologies. Connection to a heat network also provides opportunities to rapidly reduce carbon emissions in the future by changing of the lead community heat source (e.g. to heat pump or biomass technologies).

Combined Heat and Power (CHP)

Both electricity and thermal energy (for space heating and/or hot water) are produced from a single energy source, which is typically natural gas. Although not a renewable energy technology, this can be a very efficient use of fuel for some buildings and reduces their overall carbon emissions by providing electricity at a local level.

This technology is most efficient when sized to operate at a thermal ‘base load’. Both CHP and Biomass boilers perform best when sized to meet the thermal base load. The thermal base load is the amount of heat continuously required by the building. This is illustrated in the following graph showing a generic demand profile:

ECC - Solutions - combined heat and power

The base load is that below the dotted line. Peak energy demands result from increased activity and heat requirement throughout the day. Peak demands are typically met by using conventional gas boilers.

Additional systems meet the peaks of demand. This technology is best suited to buildings where there is a heat demand that matches electrical demand, such as process industries, swimming pools, community heating systems and hospitals. For this reason it is widely used in district and community energy networks, where heat use profiles from multiple buildings and process type enable a larger and more efficient system to be operated.

Possible variations on the basic system include the addition of absorption chillers, or the use of biomass or Waste materials as a fuel source.


The burning of energy crops in a biomass boiler to provide heating and hot water is considered to be a ‘carbon neutral’ process, as the amount of CO2 released during combustion is equivalent to that which is absorbed during the growing cycle of the crops.

Biomass fuel can be delivered in the form of either woodchips or pellets. Pellets contain much more energy within them, so a smaller volume needs to be stored between each delivery. Pellets can also be pumped like a fuel between the delivery lorry and the storage hopper, which makes deliveries quicker and more straight-forward. Automated systems feed the fuel through to the combustion chamber from a hopper, which needs to be refilled on a regular basis. On domestic scale systems, this is typically once per week, but depends on the system size and energy demand. Ash also has to be removed approximately once every month.

Both wood pellets and wood chip require space for storage, with woodchips requiring a larger storage volume, and delivery. It is therefore important to consider the storage and delivery access arrangements, for both new build and retrofit projects, early in the design stage if a biomass boiler is to be used.

Although it is always desirable to grow the biomass crops locally, crops are almost always grown by a separate company who sell the crop via fuels agents on the open market. Installers of biomass boilers can advise on local options. The carbon and ecological footprint associated with the cultivation and transportation of biomass fuel is something that should therefore be considered before opting for a biomass solution.

If considering this technology on an urban site, care should also be taken to ensure that the specified equipment meets the requirements of any designated smoke control zone.

Solar thermal

Solar collectors or solar thermal panels generate hot water using the thermal energy of sunlight which is used to offset conventional energy use for provision of hot water for showers and taps. This technology is well established, reliable and typically provides reasonable economic paybacks.

Panels are ideally applied to south facing roofs pitched at 30-45 degrees and can be freestanding or integrated into the roof, with pipework leading into the building and connected to a storage tank with a back-up heating supply.
Solar thermal technologies are able to benefit from the Renewable Heat Incentive. Click here for more information.

Solar photovoltaics

Photovoltaic (PV) panels or tiles convert solar energy into electricity and are available in a variety of styles, colours and materials. Panels can be freestanding, or can be integrated into the south facing facades or roofs of buildings. Conventional systems are best elevated at 30-45 degrees from horizontal. It is also possible to manufacture the PV cells into glass laminates providing the dual benefits renewable electricity and solar shading to internal spaces.

PV tiles are designed to match the colour and appearance of conventional slate tiles. They therefore can be a good solution to use on buildings within Conservation Areas. A number of other material integrated Solar PV solutions are now available on the market.

The installation of photovoltaic panels has been boosted by the Feed In Tariff for small scale electricity generation. The FIT reduces the payback period of photovoltaic panels.

Wind turbines

Turbines generate electricity from wind and are available in a variety of sizes and scales. Suitable sites must be exposed and have an average wind speed of at least 6 metres per second for a large portion of the year.
There are various options for the configuration of turbines. Small scale models can be roof mounted. Typically they have a rated output of around 1.5kW. Alternatively, small scale freestanding models are available at rated outputs of 15-250kW. These range in size up to industrial scale models that can be seen on wind farms at rated outputs of 2-7 MW.

Turbines are categorised as either horizontal or vertical axis, which relates to the axis the blades rotate around. Horizontal axis turbines are more powerful for their size, although some people consider vertical axis turbines to be more aesthetically pleasing. Most horizontal axis turbines require a wide unobstructed area in advance of the turbine the equivalent of up to 10 times its blade height, therefore they are less appropriate in heavily urbanised or forested areas.

When considering wind turbines of any scale it is crucial to consider the difference between the rated power output and the annual average output. The rated output is the maximum possible output under perfect wind conditions, which rarely occur during the year. The ratio between this maximum output and the average output over the year is called the ‘utilisation factor’, which typically ranges between 20-30% for a commercial wind farm. Small scale turbines in an inappropriate location without strong winds have been found to have utilisation factors of less than 10%.

Ground Source Heat Pumps (GSHP) and Air Source Heat Pumps (ASHP)

Heat pumps convert low grade thermal energy from a constant temperature source to higher grade energy that can be used for space heating or hot water (see diagram below). GSHP draw upon low grade thermal energy from the ground or an aquifer and ASHP draw low grade thermal energy from the air outside a building. Both GSHP and ASHP are available in different sizes, for both domestic heating and commercial premises, and the process can be reversed to provide cooling during summer months.

Heat Pump Diagram

Both GHSPs and ASHPs are better suited to new build applications as their efficiency is highest when supplying low temperature distribution systems such as underfloor heating. The use of GSHP is restricted to sites with enough land to either lay pipework in long trenches or with access to a suitable body of water such as a lake or aquifer, Whereas ASHP can be sited in any external location as long as there is good air flow.

The high ‘coefficient of performance’ or COP of a heat pump means it is an energy efficient technology – for each unit of electricity used to operate the heat pump, around four units of heating energy is produced via a GSHP and 2-3 units of heating energy via  an ASHP. The average COP over the course of a year is known as the Seasonal Performance Factor (SPF). The CoP of GSHP over a year may gradually reduce if the thermal energy of the heat source (the ground or body of water) is not sufficiently 'recharged' naturally or managed.

DECC Public Attitudes Tracker –Wave 17 published in April 2016 found that public opinion is still high (81%) in favour of  renewables with opposition to renewables very low at 4%. A majority (66%) are concerned that the UK is not investing fast enough in alternative sources of energy.

Nearly eight in ten agreed that renewable energy developments should provide direct benefits to the communities in which they are located (77%), whilst seven in ten (70%) agreed that renewable industries and developments provide economic benefits to the UK. Just over half said they would be happy to have a large scale renewable development in their own area (56%).

Sector specific issues

Different types of buildings have individual requirements in terms of energy use. Some points for consideration are listed below.


Passive systems, such as natural ventilation and daylighting are traditional solutions for domestic buildings. Passive solar design can be particularly effective, with south facing sun spaces giving free energy and pleasant living conditions (note these are not the same as glazed conservatories). These must be design appropriately to avoid excessive solar gain and overheating .

An alternative low energy approach which is emerging from the influence of Scandinavian design is the construction of an extremely well insulated and air tight building with a mechanical ventilation system incorporating efficient heat recovery. This building design is sometimes referred to as PassivHaus.

Small scale renewables can be appropriate. Technologies which lend themselves to this particular sector include solar thermal and photovoltaic panels, heat pumps and biomass boilers. Micro Combined Heat and Power (Micro CHP) units for domestic use are gradually emerging onto the market.
Historic and Listed Buildings also present specific issues and circumstances that need to be taken into account when seeking to implement energy efficient and sustainable solutions.

Listed Buildings and buildings within Conservation Areas are subject to tighter planning controls than the rest of the housing stock in regards to changes to facade and the fabric of the building. Specific guidance on how to achieve energy efficient refurbishment or renovation, and the use of sustainable solutions within historic and listed buildings can be accessed at the links below:

Construction Industry Publications.
English Heritage publication "Energy conservation in traditional buildings".


Although natural ventilation is typically the preferred choice, it is not always appropriate in commercial developments. If the site is noisy, has poor air quality or high internal heat gains from intensive use of IT or other equipment, it may be more appropriate to seal the building and use a mechanical ventilation system. In this case, measures for energy efficiency should be adopted, such as free cooling or heat recovery.

The use of daylight should be promoted and could be combined with control systems to switch off electric lighting when not required. This is typically a significant form of energy consumption in commercial buildings.
Atria can be particularly effective in this sector and can be used to bring natural light in and encourage air movement in deep plan spaces.
Renewable and low carbon energy technologies can be suitable, although biomass boilers for heat or Combined Heat and Power do not tend to be suitable for most commercial developments due to their intermittent occupancy and relatively low heat demand.

As mentioned previously, it can be beneficial to reduce unregulated energy consumption in operation. IT and media equipment constitutes an increasing proportion of ‘unregulated’ energy loads, particularly in IT-rich environments such as offices and schools. IT equipment requires electricity to operate and releases waste heat, which can contribute to rooms overheating and becoming uncomfortable, or lead to the use of air-conditioning that requires even more energy to be consumed.

The procurement of efficient IT equipment reduces the energy consumed to run IT devices and helps to avoid the use of air-conditioning. Efficient IT features include:

  • Low-energy flat screen displays (LED displays are emerging on the market)
  • Thin client devices and virtual desktop management
  • Power saving measures and procedures, such as automatic hibernation mode or night-time power-down
  • Behaviour change campaigns, such as stickers/posters to encourage ‘switch off your PC for lunch’
  • Hosting IT server activities at an offsite ‘green data centre’, whose energy efficiency will be measured as a Power Usage Effectiveness


Passive measures are typically desirable in primary and secondary schools. The activities in further and higher education buildings can require a more intensive services strategy; again efficient equipment should be specified.

Controls systems that turn lights off in unoccupied classrooms, corridors and toilets should be incorporated.

The use of renewable and low carbon energy technologies can be particularly appropriate in education buildings, to raise awareness of energy issues. There are several examples of schools with small scale wind turbines in Hertfordshire and across the UK. It should however be remembered that even educational installations should only go ahead if they will generate a meaningful quantity of energy that the school is able to use. The educational benefits can backfire if the energy meters show that little energy is being generated and even where energy generation is satisfactory, installations will only make economic sense if the majority of that energy is used on site and not exported to the national grid.  


Renewable and low carbon energy technologies can be particularly appropriate for hospital buildings. A large roof space is typically available for installations of solar thermal or photovoltaic panels, although roofs can also be occupied by significant plant equipment.

Combined heat and power systems lend themselves to this type of building, as there is a high and constant energy demand for both electricity and heat. Ground source heating/cooling can also be effective where site conditions permit.


The approach to energy efficiency on industrial buildings very much depends on the activities being carried out. For example, there may be processes on site which either demand heat and/or generate waste heat, which could be reclaimed and used to heat other areas of the building.

Large industrial buildings may benefit from using radiant heating rather than convective or warm air heating.  



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Performance and feature cookies – these cookies help to improve the performance and feel of this website, for example providing you with personalised services.

Take a look at a list of cookies we use on our website:

NameTypeHow we use itHow long we use the information for



Required functionality

An automatic cookie set by our software. 

Just for the time you are on our website.



Required functionality

An automatic cookie set by our software. 

Just for the time you are on our website.


Required functionality

To track the effectiveness of our website using Google Analytics. 

2 years


Performance and feature

To save the pages that you visit by clicking the heart at the top of the page. 

1 month


Performance and feature

This stores your postcode (or partial postcode) when we ask you for your location.

Just for the time you are on our website or 30 days (you choose this).


Performance and feature

This stores your location as a pair of latitude / longitude coordinates.

Just for the time you are on our website or 30 days (you choose this).


Performance and feature

This keeps a history of all answers submitted to the ready reckoner.

This is set in the control for each ready reckoner. If you haven't interacted with the ready reckoner for the set amount of days, the cookies are deleted.


Performance and feature

This keeps a history of what content cards are clicked on when using the ready reckoner.

This is set in the control for each ready reckoner. If you haven't interacted with the ready reckoner for the set amount of days, the cookies are deleted.


Required functionality

This used to track user sessions on forms hosted on

Just for the time you are on our website.

Third party cookies

There are links and content from other sites and services on our website. These sites and services set their own cookies.

Below are a list of cookies that the other sites and services use:

Service namePurposeMore information

Google analytics (_utma/b/c/z)

These are used to compile reports for us on how people use this site.

Cookies of the same names are also used for the same purpose by other websites such as Building FuturesCountryside Management Service and Hertfordshire LIS.

Visit the Google Analytics website for more information about the cookies they use.

You can prevent data from being collected and used by Google Analytics by installing Google's Opt-out Browser Add-on.

Google Translation - googtrans

This cookie is used to remember which language to translate each page into if you have chosen to do so.

It expires at the end of your browser session.


We use a Bing cookie to track the success of our marketing campaigns and make them more efficient.

Visit Bing to find out more about their cookies.


We use a Google cookie to track the success of our marketing campaigns and make them more efficient.

Visit Google to find out more about their cookies.


We have a number of presences on Facebook, which we may link to. Facebook may set some of its own cookies if you follow these links.

Visit Facebook to find out more about their cookies.


We have a number of presences and feeds on Twitter, which you may wish to follow or read from this website. Twitter may set some of its own cookies.

Visit Twitter to find out more about their cookies.


We have a YouTube channel, which we may link to. YouTube may set some of its own cookies if you follow those links.

Visit YouTube to find out more about their cookies.


This ASP.NET_Sessionid cookie is essential for the Netloan secure online payments website to work, and is set when you arrive to the site. This cookie is deleted when you close your browser.



This session cookie is set to let Hotjar know whether that visitor is included in the sample which is used to generate funnels.

Visit HotJar to find out more about their cookies.


These cookies are set to help us report on how people are using the site so we can improve it.

Visit Siteimprove to learn more about their cookies.