Confused by jargon? Collapsing under abbreviation overload? At Hawton Mead we always try to explain things clearly and simply. Here’s a guide to some of the terminology:


A campaign originally launched with the target of reducing carbon emissions by 10% in 2010, which has now been extended to target a 10% reduction every year. See


Action taken to respond to the predicted impact of unavoidable climate change, including the design of buildings not only to make them more energy efficient but also to improve their resistance and resilience to climate change. We are experts in sustainable adaptation.


A network of individuals and companies, which promotes and develops standards for sustainable building. See

Airtightness (air leakage rate)

A measure of how much air leaks through the building fabric via uncontrolled ventilation (excluding movement through intended ventilation measures). Such leakage increases energy demand, as heated air is lost and replacement air needs to be heated. We can show how to improve airtightness.

Airtightness Testing

Measurement of airtightness/leakage during a pressurisation test, expressed as the volume of air that leaks per square metre of the fabric per hour, when the building is subject to an internal/external pressure differential of 50 Pascals. We can carry out airtightness tests.


Organic matter, such as wood and other plant materials, or organic waste, which can be used as a renewable fuel. We can advise on biomass burning options.


The Building Research Establishment, now known as the BRE Group.


(BRE Environmental Assessment Method) An internationally-recognised method for assessing the environmental performance of larger buildings. We can arrange BREEAM assessments. See

Bungaroosh (or bungarouche)

A building material used in Brighton and the surrounding areas in Sussex by Georgian and Victorian builders to build walls. It is made up of lime mortar poured into shuttering and anything else that came to hand was bunged in too. This could be old bricks, bits of flint, odd lumps of wood, chalk and infact anything solid. We are familiar with Bungaroosh and can advise on how to improve its energy efficiency.

CAT (Centre for Alternative Technology)

An educational organisation devoted to sustainable technologies and ways of life. See

CCHP (Combined Cooling Heat and Power, aka trigeneration)

An extension of CHP, in which recovered heat is processed through an absorption cooling cycle, to be used for cooling as well as, or instead of, heating. We can advise on the selection and installation of CCHP units.

CHP (Combined Heat and Power)

The simultaneous generation of usable heat and power (usually electricity) in a single process. The heat can be used to provide hot water or steam. CHP units can achieve 70% efficiency, compared with 40-50% for conventional power generators which waste the heat they produce. They can be small enough to install at the point of use, giving even greater efficiency compared with centralised power stations which incur significant losses through long-distance transmission and distribution. We can advise on the selection and installation of CHP units.

Code for Sustainable Homes

The statutory standard for design and construction of new homes in England and Wales, with nine sustainability criteria (including minimum standards for energy and water use) and a rating system of levels from 1 (lowest) to 6 (zero carbon). We can design, evaluate or modify plans to ensure that buildings will achieve the desired rating.

Design for Future Climate

A government-funded competition to finance strategies to adapt UK buildings to the changing climate. We are involved in the judging process. See


Adapting existing homes to make them more energy-efficiency and sustainable. We can show you how. See

Energy Saving Trust

An independent UK-based organisation, jointly funded by government and the private sector, which provides free advice and information and promotes action that leads to reduction of carbon emissions.


In the context of heat loss, the entire outer structure of a building, including walls, roofs, doors, windows and floors.

EPC (energy performance certificate)

A record of the energy efficiency of a building, plus recommendations as to how it could be improved. In England and Wales, an EPC is a legal requirement for all new buildings and for existing buildings when they are sold or let to a new tenant. An EPC must be completed by an approved assessor, using approved methodology such as the SAP or RdSAP. We can conduct assessments and issue EPCs.

FIT (Feed in Tariff)

An incentive to encourage the installation of solar PV panels and other renewable electricity-generating technologies (eg, wind turbines) by householders and communities. Those installing the technology before April 2012 will receive 43.1p per kWh of electricity generated, with an extra 3.1p payable for each kWh exported to the grid. Tariffs are likely to be reduced slightly for equipment installed after April 2012, but all are guaranteed for 25 years and will be index-linked. See

Future proofing

Designing or constructing a building so that it can be easily adapted at a later date. For example by making provision for future installation of renewable technologies. We can show you how.

Green Deal

An incentive to be launched in autumn 2012, which will provide a low-interest loan to homeowners, secured on their properties, to cover the cost of introducing energy-efficiency measures. The loan will be paid back via energy bills, but savings on the bills should exceed the cost of loan repayments. We will advise on how to obtain the Green Deal. See

Green Roof (aka Living roof)

A roof covered with live vegetation in a layer of growing medium on top of a waterproof membrane. Green roofs can provide insulation, support biodiversity and reduce a building’s contribution to the heat island effect, as well as absorbing water and controlling run-off and flooding from heavy rainfall. We can advise on feasibility, options, installation and maintenance.

Grey Water Recycling

The process of collecting, treating and storing used shower, bath and tap water for re-use in WC's and washing machines. We can advise on grey water recycling systems.

Heat Island Effect

The local temperature increase associated with a building or a built-up area, caused for example by absorption and release of heat by building materials, or heat loss from inside buildings. We can advise on ways of reducing the heat island effect.

Heat Pump (air source)

Heat is extracted from the air outside a building by a heat exchanger (like a refrigeration unit). It is used to warm water (air-to-water system) or to produce warm air for space heating (air-to-air system). Heat pumps work even when the outside temperature is very low. We can advise on suitability, selection and installation.

Heat Pump (ground source)

Heat from the ground is absorbed into a fluid circulating around a loop of pipe buried underground (eg, in a garden). It passes through a heat exchanger to produce low-level heat, then through a compressor which concentrates the heat to a temperature high enough to heat water for space heating and hot water supply. The ground loop fluid, now cooled down, goes back underground to absorb more heat. We can advise on suitability, selection and installation.


Various financial incentives are available or planned to encourage the uptake of energy-efficiency measures and renewable energy generation – see FIT (Feed In Tariff), Green Deal, Renewable Heat Incentive. We can advise on how to take advantage of these incentives.

MHVR (Mechanical Ventilation with Heat Recovery)

A ventilation system in which a heat exchanger extracts heat from outgoing exhaust air and uses it to warm incoming fresh air. We can advise on suitability, selection and installation.


Slowing down global warming by reducing greenhouse gas emissions.

NHER (National Home Energy Rating Scheme)

A UK accreditation scheme for energy assessors, and a rating scale for the energy efficiency of housing, operated by NAS (National Energy Services). We can carry out NHER SAP assessments. See

Passive House (aka Passivhaus)

A voluntary standard which ensures a comfortable indoor temperature in summer and in winter without needing a conventional heating system. To permit this, it is essential that the building’s annual demand for space heating does not exceed 15kWh/m2year. The minimal heat requirement can be supplied by heating the supply air with the ventilation system – a system that is necessary in any case.  The standard has been named ‘Passive House’ because the passive heat inputs delivered by solar irradiation through the windows and provided internally by the heat emissions of appliances and occupants essentially suffice to keep the building at comfortable indoor temperatures throughout the heating period. We are one of the UK’s leading authorities on Passive House design and assessment. See


An ethical philosophy for sustainable living with minimal environmental impact. We can advise on how to apply permaculture principles to, for example, landscaping and gardening, using methods based on natural ecology to minimise artificial inputs, watering need, etc.

PV (photovoltaic)

A system using arrays of cells containing a crystalline material that captures solar radiation and converts it into electrical current. We can advise on suitability, selection and installation.

RdSAP (Reduced data SAP)

The UK government’s recommended system for measuring the energy rating of existing homes, similar to the SAP for new build, but with a reduced data set since many SAP data items cannot be seen in an existing building. The missing data are estimated from a database of typical values for different types of buildings. We can carry out RdSAP assessments and issue energy performance certificates (EPCs).


Adapting existing homes to make them more energy-efficiency and sustainable. We can show you how. See

Retrofit for the Future

A government-funded scheme for retrofitting social housing. In Phase 1, £3.5 million was awarded to 193 projects, which were evaluated by a panel of judges. In Phase 2, 87 of these projects were awarded contracts to build prototypes demonstrating exemplary energy efficiency and deep cuts in carbon emissions. These will be evaluated for at least two years by the Energy Saving Trust, to assess their performance and their potential for large-scale implementation. We are involved in the judging process. See

RHI (Renewable Heat Incentive)

A government-backed incentive scheme, similar to the Feed in Tariff (FIT), which will pay a fixed amount per kWh of renewable energy generated by solar thermal panels, heat pumps and biomass boilers. This will be introduced in autumn 2012. Until then, a range of grants will be available via the Renewable Heat Premium. We can advise on how to access these incentives and how get the best returns. See

SAP (Standard Assessment Procedure)

The UK government’s recommended method for measuring the energy rating of new residential buildings, based on annual energy costs for space and water heating and lighting, and carbon emissions. It is used to check for compliance with building regulations. Assessments include design stage predicted energy assessments (PEAs), post-construction reviews (PCRs) and energy performance certificates (EPCs). We can carry out SAP assessments and issue EPCs.

SBEM (Simplified Building Energy Model)

A software tool developed by BRE (see above), which analyses the energy consumption of larger buildings in compliance with UK building regulations.

Service Voids / Service Ducts

A design feature in which all services (pipes, cables, etc.) enter and leave a building via a single internal space or duct, rather than having multiple entry points causing gaps and/or thermal bridges in the building envelope. We incorporate service voids/ducts into our designs wherever possible, to maintain airtightness and reduce heat loss.

Smart Meter

An advanced meter that monitors consumption of electricity, gas and water, giving householders accurate, real-time information on their usage and helping them to manage it more efficiently. The information is also communicated via a network to utility companies, enabling more accurate billing and making it faster and easier to switch suppliers.

Solar Gain / Solar Shading

Space heating from solar energy, which can be influenced by the orientation of a building, materials used, the type and position of glazing, shading, etc. We can advise on how best to take advantage of solar gain, and how to use solar shading to prevent overheating.

Solar Panels

Panels placed outdoors (eg, on the roof of a building) to capture solar energy. There are two types: PV panels which generate electricity (see above), and flat plate or evacuated tube panels which heat water. We can advise on suitability, selection and installation.


A campaign to develop a national network of old homes which have undergone an energy-efficiency retrofit, to serve as models and inspiration for people to make their own homes more sustainable. See

Thermal Bridging

Thermal bridges occur where a material of relatively high thermal resistance (eg, a layer of insulation) has a material of lower thermal resistance (eg, steel wall ties) passing through, providing a path for heat loss. In a well-insulated building, thermal bridges are responsible for a high proportion of the residual heat loss, so eliminating them is a crucial part of sustainable building design. We can identify thermal bridging problems and design ways of overcoming them.

Thermal Imaging

The use of specialised cameras, which capture infrared radiation, to produce images showing heat distribution. Thermal imaging can be used to identify ‘hot spots’ where heat is being lost from a building. We can carry out thermal imaging studies.

Thermal Mass

The capacity of structural materials (eg, concrete) to absorb, store and release heat, a property which can be exploited in the design of the building, to help regulate temperature. We can advise on the use of thermal mass in sustainable building design.

Thermal Performance

The physical properties of a home which affect the rate of heat loss from it, such as insulation, physical dimensions, ventilation, glazing, orientation, etc. We can measure thermal performance and design ways of improving it.

Thermal Store

A hot water store which provides mains pressure instant hot water and also acts as a buffer for space heating. We can advise on the use of thermal stores in sustainable building design.


A measure of the rate of heat transfer through the fabric of the building, expressed in W/m2K. A low U value means lower heat transfer, and thus better thermal performance. We can measure U values and design ways of improving them.