The whole house, fabric first approach to retrofit

The whole house approach

This approach considers a broad range of aspects: your comfort, your home and its history, indoor air quality and ventilation, moisture inside your home, energy use and bills reduction, as well as CO2 emissions. This holistic view helps to identify your options and how they can work together. It also reduces the risk of unintended consequences. 

For example, if the house becomes well insulated and more airtight but the ventilation strategy is not upgraded to provide the right level of ventilation, the risk of mould related issues increases.

Fabric first principles

By adopting fabric-first principles we prioritise energy saving measures first in order to make our homes more comfortable and affordable to heat. This is before we start to consider changing heating and hot water systems.

Although it can be disruptive and costly to carry out fabric improvements, it is more carbon cost effective as you save more over the life-cycle of these measures than you do with system upgrades.

Prioritising fabric improvements will reduce upfront (capital) heating system costs. Improving the insulation performance of homes results in the need for smaller sized boilers and radiators, which means lower energy running costs.

1. Remedial work

Before any improvement works are carried out, it is essential to make sure that any problems have been fixed and that the house is in a state of good repair. This extends the lifespan of any works to improve your house for as long as possible.

Example measures include:
A. Roof repair or replacement
B. Gutter and/or downpipe repair
C. Structural crack repair
D. Install a French drain or carry out remedial damp proofing
E. Repointing or render repair

2. Insulation

Once any existing issues are fixed, the building fabric (roofs, walls, floors) should be improved so the heat losses are reduced. This can be done by adding insulation, which has a long life compared to other measures such as boilers, ventilation and renewable energy systems.

The heat loss percentages from the roof, walls and floor of a typical home are shown. These can be reduced by improving insulation.

Example measures include:
A. Loft or pitched roof insulation
B. Replace window frames and/or glazing
C. Flat roof insulation
D. External or internal wall insulation
E. Floor insulation (solid or suspended)

3. Airtightness

Airtightness is essential for a comfortable, draught free, and energy efficient house. Improving it means removing all the gaps, cracks, and unwanted openings in the external envelope of your home which comprises the roofs, walls, windows, doors and floors, in order to minimise leaks and draughts.

The heat loss percentages from the windows and doors of a typical home shown. These can be reduced by improving airtightness.

Example measures include:
A. Draught strip loft hatch
B. Refurbish and seal door/window frames
C. Seal suspended ground floors
D. Draught strip roof and intermediate floors
E. Seal and cap off chimney

4. Ventilation

Insulating and increasing airtightness in houses makes ventilation a key consideration for the retrofit works. Good air quality is essential to a healthy, comfortable home; reducing stuffiness and maintaining the health of residents. It is also essential to deal with excessive humidity, which if not controlled, can lead to condensation, damp, mould and health problems such as respiratory illnesses. Appropriately controlled ventilation is required to help maintain good relative humidity levels.

Example measures include:
A. Whole house supply and extract system
B. Extract purge ventilation
C. Increase background ventilation through wall vents
D. Increase background ventilation via trickle vents on windows and purge ventilation via windows which can open

5. Building services and renewable energy

Once the house is better insulated and less fuel is used for heating, the building services (heating, water, electricity) should be made more efficient. Building services have relatively short lives compared to insulation and they need to be replaced more regularly. Once the heating demand is lower and the building services are more efficient, the potential for renewable technology should be considered.

Example measures include:
A. Solar panels (photovoltaic or solar thermal)
B. Energy efficient appliances
C. Radiators
D. Underfloor heating
E. Hot water cylinder
F. Heat recovery technology
G. Replacement boiler
H. Ground source heat pump
I. Air source heat pump

Carbon emissions

Reducing the energy demand of your home through fabric improvements has the benefit of reducing carbon emissions. It can also save you money on energy bills. In many cases, reducing emissions beyond fabric improvements means tackling your space heating source. This requires a switch from domestic fossil fuel boilers and transitioning to electric heating and hot water.

Due to the UK’s distorted energy prices (gas is significantly cheaper than electricity), this could have a negative financial impact on your budget and bills, especially if energy demand is not significantly reduced before switching. Focusing on energy use and switching to electricity future proofs your home as we head towards net zero and a renewable and low carbon future.

The toolkit is used in 3 stages:

See the full instructions