RETROFIT

Retrofit is the process of improving the performance of a building after it has been built, typically through installing insulation, reducing draughts, and improving the ventilation and heating systems. In order to meet the climate crisis head-on it’s vital that we improve the carbon impact of heating our homes by reducing heat loss and making the heating systems more energy/carbon efficient. It is also a major health issue as poorly ventilated, draughty, cold, and damp buildings create an unhealthy internal environment with condensation and mould growth.

Understanding how an existing building works in terms of moisture and ventilation is crucial to avoid increasing the risk of condensation inside homes. Historic buildings were built using vapour permeable materials and ventilated by draughts and open chimneys. Over time, many homes have had impermeable materials added and chimneys & draughts blocked up. During a retrofit, inappropriate past work may need to be remedied, and new work should be carried out with intelligent use of vapour permeable materials to avoid further harm the building. Ensuring the house is well ventilated is crucial, and this becomes even more important if airtightness is improved or insulation is added. Both of which are important for reducing energy demand, and improving comfort.

BEFORE RETROFIT

Existing building showing some of the common sources of moisture and weak points for airtightness in buildings.

AFTER RETROFIT

Well ventilated, airtight, fully insulated, warm, and dry home with a low-carbon heating system after retrofit.

RETROFIT PROCESS

To make the biggest energy savings and create a healthy home, retrofit projects should take a “fabric first” approach by prioritising:

Fixing defects like leaking gutter, damaged roofs, cracks in render, faulty DPCs, brick pointing, etc.
Ventilating properly to provide a reliable source of fresh air and remove moisture, CO2, VOCs, radon gas, and other polutants, for the health of occupants and the building. Ideally with a whole house ventilation system with heat recovery (MVHR), or a continuous extract system if MVHR is not viable.
Improving airtightness to minimise draughts and heat loss, and to reduce the risks created by moisture being carried into the building fabric by air movement.
Providing a continuous layer of insulation generally using hygroscopic, vapour permeable materials around the entire building to keep heat in without trapping moisture.
Upgrading the heating system with a low-carbon heating system, such as an air source heat pump (ASHP).