Eco Glossary

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Airtight construction

The method of making new or refurbished buildings highly airtight to minimise ventilation losses; often associated with MVHR (see below).

Biomass boiler

Boiler mostly fueled by carbon-neutral wood, normally as pellets, but can also be chips or logs. Significantly cheaper to run than oil in off grid areas and will receive RHI payments (see below) from 2014 and RHPP grants (also see below) in the interim.

Condensing boiler

A type of boiler that captures more usable heat from its fuel. Its
efficiency is made possible by the boiler’s ability to condense water vapour from flue gases and recover latent heat. Most modern boilers are condensing and can be 10-20% cheaper to run than old ones.


Lots of heat is lost through draughts so this is a priority for saving
money. Typical draughty areas of a house include chimneys, loft hatches, windows and doors, around skirting boards and floors.

Energy Company Obligation (ECO)

The Energy Company Obligation (ECO) is a grant paid by the big energy companies and assessed by your Green Deal Provider. There are three routes for obtaining ECO funding:

Carbon Saving Community Obligation – targeting the poorer postcodes.

Affordable warmth – grants for those on means tested benefits.

Carbon Savings Obligation – helping those in ‘hard to treat’ properties, notably by supporting wall insulation, regardless of income.

Energy controls

Nearly one third of heating systems lack one or more of the basic
controls: thermostatic radiator valves (TRVs), room thermostats or programmers. If any of these is missing, heat losses (and bills) can rise by 5 - 10%.

Feed In Tariff (FIT)

The Feed In Tariff pays a fixed sum for each unit of electricity generated through domestic renewable technologies, mainly photovoltaic panels. At the moment this payment is guaranteed for 20 years. Additional money is also paid for electricity exported to the grid.

Flue gas heat recovery (FGHR)

Even a condensing boiler vents useful heat in the flue gas,
but this can be recovered to preheat water using a simple FGHR unit, cutting bills by 5 -10%.

Green roof

A roof that is partially or completely covered with vegetation and a growing medium, planted over a waterproof membrane. This preserves vital habitat in urban areas.

Grey water recycling

Collecting waste water from sinks, showers and baths and reusing it for toilet flushing or watering the garden.

Ground floor insulation

For suspended floors, mineral wool or rigid insulation boards are
installed between joists. For solid floors, rigid insulation board is placed on top of the solid floor and under a finishing layer. Installing thicker carpets and/or insulated carpet underlay
can also help cut energy loss.

Heat pump

A heating unit that extracts heat from the external environment, e.g. air, ground, or water and uses it to heat a building. Heat pumps are powered by electricity, but extract many times more useful heat energy for each unit of electricity consumed. They are particularly economic compared to oil or electricity in off grid areas.

High performance glazing

Windows that are designed to minimise heat loss, for example
through an insulated frame, a low E coating, an inert gas filled cavity or triple glazing.

LED lighting

A very low energy form of lighting (light-emitting diode) which uses significantly less energy, is long-lasting and cheap to run. LEDs are now available for most light fittings and can pay for themselves in a year or two.

Low energy appliances

All appliances are rated from A to G, with appliances rated A and
A+++ for refrigeration using the least energy. Washing machines and dishwashers are also rated for the amount of water they use per cycle. Old fridges and televisions in particular are very wasteful of electricity compared to modern ones.

Low water goods

Taps, showers or toilets that are designed to use less water than typical plumbing fittings, typically by restricting flow or limiting flushes.

Mechanical ventilation with heat recovery (MVHR)

A ventilation system with a heat exchanger that recovers warmth from outgoing air to warm cooler incoming fresh air. This requires a high level of airtightness to be effective.

Natural materials

Products that come from plants or animals – including sheep’s wool insulation, sweet chestnut cladding, sustainably sourced timber paints and clay plaster. Natural materials tend to be more sustainable than artificial materials and allow breathability
and movement of moisture.

Passive solar design

By ensuring that a building absorbs the maximum amount of warming sunshine in winter, fuel used for heating can be reduced. Typically this involves orienting new buildings toward the south with a large glazed area to receive the low winter sun, or even a conservatory on the southern facade.

Passivhaus standard

A low energy standard that reflects the principles of high levels of
insulation, airtight construction, high performance glazing and a mechanical ventilation system with heat recovery. The target of Passivhaus is little or no energy use.

Photovoltaic (PV) panels

Panels usually mounted on a roof to convert sunlight into
electricity. Electricity generated using PV panels attracts a payment known as the Feed in Tariff (FIT).

Rainwater harvesting

Collecting water that falls on a roof and using it at home for
washing clothes, flushing a toilet or watering the garden.

Renewable Heat Incentive (RHI)

The Renewable Heat Incentive (RHI) is a government subsidy that will apply to technologies producing heat rather than electricity; i.e. solar thermal, biomass boilers, and heat pumps. It is expected to start in 2014 and run for 7 years. In the interim, generous one-off Renewable Heat Premium Payment (RHPP) grants are available.

Secondary double glazing

Insulation of windows by fixing a glazed panel on the inside,
which can save almost as much as full double glazing, at a fraction of the cost and is particularly suitable for conservation areas.

Solar thermal panels

The sun’s energy is used to directly heat hot water, via either flat
panels or evacuated tubes placed on the roof. From 2014, the Government plans to introduce the Renewable Heat Incentive, which will give payments for solar heat and already gives a
generous PHPP grant.

Solid wall insulation (SWI)

Solid walls can be insulated externally or internally. Walls are
usually insulated externally by fixing insulation boards to the wall and then finished with rendering or cladding. Walls are internally insulated by fixing rigid insulation boards to existing walls or by building a stud wall filled with mineral wool or equivalent which is then dry lined with plasterboard. Walls can lose 40% of heat so insulation is a priority.

Timber frame

A method of wall construction using timber studs, finished with dry lining boards on the inside and cladding outside, which creates a void that is easy to fill with insulation. Timber also has low embodied energy and helps fix carbon, which makes it a highly sustainable material.

Woodburning stove

Having a stove provides heat directly to the main living area, whilst
helping minimise fossil fuel use from gas central heating, thereby cutting bills and carbon emissions.