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Energy efficiency

Energy loss from buildings

Understanding how buildings lose energy helps us to conserve energy in buildings.


Most heat loss from a building occurs through the walls.

The amount depends on:

  • building material
  • wall construction
  • insulation


Around 25% of heat loss from a building is through the roof.

The amount depends on roofing:

  • construction
  • material
  • insulation


Between 10-20% of energy loss from a building is through windows.

The amount depends on the window:

  • type
  • material
  • draught-proofing
  • glazing


Around 15% of energy loss from a building is through doors.

The differences between modern and traditional buildings

Traditional (historic) buildings, which can include listed buildings, perform differently from modern buildings.

Historic England defines traditional buildings as:

  • those likely to have been built before 1919
  • those with a solid-wall construction
  • those with no damp-proof course
  • those with bay or sash windows, single-glazed

The fabric of traditional buildings needs to ‘breath’, to release and absorb moisture.

Traditional buildings need around twice the amount of ventilation of modern buildings.

Moisture moves through traditional buildings until it evaporates.

Modern, impermeable building products obstruct this process.

Traditional buildings need higher levels of ventilation.

Using modern materials and methods (such as uPVC and double-glazing) in traditional buildings:

  • restricts air flow
  • traps moisture inside
  • speeds up decay

Methods of Energy Conservation

Ordered from least intrusive to most.

Least intrusive methods are most appropriate for use in listed buildings.

Energy efficient products

  • change incandescent lamps to energy efficient versions
  • buy energy efficient white goods

Such products would not need prior listed building consent.

Loft insulation

One of the easiest and cheapest ways of improving a building’s energy efficiency.

In traditional buildings natural insulation materials, for example:

  • sheep’s wool
  • hemp fibre

are better than modern materials, such as:

  • fibreglass
  • mineral wool

Modern materials tend to hold moisture, increasing the risk of:

  • damp
  • timber decay
  • mould growth

Loft insulation is unlikely to need prior listed building consent.

Pipework and hot-water cylinders can also benefit from insulation.

Fitting this insulation does not need prior listed building consent.


Account for around 60% of all domestic CO2 emissions.

Using an energy efficient boiler cuts your home’s CO2 emissions and saves money.

In listing buildings:

  • A new location and / or piping for a new boiler is likely to need prior listed building consent.
  • Replacing an old boiler with a new boiler in the same location and same piping may not need prior listed building consent.


Traditional buildings may be over-ventilated.

Cold air can get in through:

  • windows
  • doors
  • letter boxes
  • loft hatches
  • cat flaps

Draught-proofing is one of the best and least intrusive ways to:

  • improve comfort
  • reduce heat loss
  • reduce noise
  • reduce dust ingress

If fitted with care many draught-proofing measures are compatible with building conservation principles.

They are typically reversible, have few lasting consequences.

They cause no loss of historic fabric.

For casement windows the process is simple.

A wide range of products are available.

For example, durable rubber seals which are discretely rebated into the window frame.

Draught proofing of double hung sash windows is more complex.

Steps include:

  • replacing the parting bead with a new component
  • incorporating rubber blades to maintain the seal at the sides
  • fitting compression seals to the meeting rail, window head and sill

Draught-proofing may need prior listed building consent.

Using existing shutters can also help cut down heat loss through windows.

Secondary glazing

An alternative to installing new double-glazed windows.

It keeps the existing windows and preserves the property’s external appearance.

It improves energy efficiency.

There are many options for secondary glazing including:

  • selecting the best method of opening
  • devices which avoid condensation build-up such as a one-way trickle ventilator
  • use of double-glazed secondary glazing

Secondary glazing is encouraged in listed buildings as an alternative to double-glazing.

Secondary glazing is likely to need prior listed building consent.

Wall insulation

Around a third of heat lost in homes is through walls.

Insulating them improves a building’s energy conservation.

With their solid walls, traditional buildings can be insulated using three methods:

  • external cladding
  • internal insulation
  • using wall battens and internal lining (dry-lining)

Wall insulation is likely to need prior listed building consent.


Improves a home’s comfort by reducing draughts.

Double-glazing is not encouraged in listed buildings.

May involve the loss of the original windows and the introduction of details that ruin a traditional building’s character.

For example, including thicker glazing bars and beading instead of putty.

In a large window with a single glazing bar, the difference will not be as noticeable as in a small-paned sash.

Double-glazed windows and doors need prior listed building consent.

uPVC windows and doors

uPVC windows and doors are damaging to the:

  • character
  • appearance
  • preservation

of traditional buildings.

Replacing timber with uPVC is expensive.

Any effects to property value rarely outweigh the expense.

Installing such windows in an historic building can in reduce its value.

uPVC windows are not cheaper in the long run.

They are vulnerable to heat, UV light and have a life of approximately 25 years.

If timber windows are 60 years old or older, it is likely the timber is old growth-dense and durable wood that is now scarce.

When they fail uPVC windows cannot be repaired.

Old buildings need to 'breathe' so eliminating all draughts can lead to condensation and damp problems.

The process of uPVC manufacture and disposal is damaging

They look wrong in a historic building.

Changes to windows and doors in listed buildings needs prior listed building consent.

Changes to windows and doors in commercial properties and flats needs planning permission.

In conservation areas, changes to a house’s windows / doors may need planning permission.

Before undertaking any work check with the Council’s Development Management Section.

They can confirm if your need prior consent or permission from the Council.

Work carried out without the required consents and / or permissions may result in enforcement action.

More information

The Energy Saving Trust is an independent organisation working to address climate change.

Energy Saving Trust [external link]

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