Do you have an old home? Or are you thinking of buying one?
Many of us love living in older properties due to their character, sense of space and period features. But many of us despair at how cold, draughty and expensive to heat they are in winter.
But this doesn’t need to be the case. It is possible to dramatically improve your comfort during the winter without damaging the historic character you fell in love with.
Why would I retrofit my older property?
It’s estimated 80% of the UK housing stock that will exist in 2050 is already built. Many of these were built 80-plus years ago.
This was at a time when environmental standards were much lower with little or no consideration given to sustainability and comfort.
As a result there is plenty of opportunity to improve an older building. Both to deliver efficiency benefits as well as to create happy and healthy homes for you and your family.
What measures can you use to improve your comfort?
These fall into 4 main areas:
- Thermal insulation: Wrap the building in a warm blanket to keep the heat in
- Ensuring thermal continuity: Cold bridges need to be minimised so there are no cold spots for heat loss or condensation issues
- Air-tightness: Avoiding heat loss through uncontrolled air-leakage
- Ventilation: Improving ventilation to ensure good air-quality and humidity control
But it’s really important to design these measures in a holistic way when working with a historic building. Otherwise there could be significant, unintended consequences: both to the building and to its occupants.
The risks of unintended consequences:
These can include:
If poorly designed additional insulation can lead to condensation inside the building’s construction. This could damage the building and encourage mould growth out of sight. This can all have serious implications for the longevity of an existing building.
Breaks in the insulation, especially if these are isolated, can lead to cold spots. These lose heat but also provide potential surfaces for condensation and unhealthy mould growth.
Reduced air quality:
Making a building more air-tight will certainly help with heat loss but can conflict with its original ventilation strategy. Carefully designed ventilation is critical to ensuring there is plenty of clean, healthy air.
What information is available to help me understand these risks?
The Sustainable Traditional Buildings Alliance [STBA] has some useful tools for understanding the possible risks of retrofit measures in traditional buildings.
The responsible retrofit guidance wheel is especially good. It identifies which other elements of a building might be impacted on by a measure and also what consequences should be considered.
The STBA responsible retrofit guidance wheel
The importance of a step-by step retrofit:
A proper phased plan is key to avoiding any unintended consequences with your retrofit.
It will also help you to understand major development milestones and how your building might perform as the works are completed.
By taking an informed and holistic approach you will ensure you gain the maximum benefit at every stage of the retrofit.
How does a retrofit strategy differ in an older building?
A different approach to retrofit is needed in a property older than 80 years old to avoid the risks of unintended consequences.
Air-tightness and good quality ventilation can make a huge difference to your comfort. Prioritising these over other measures will mean you’re more likely to have a comfortable but risk free build.
For example on our Grindle Cottage project we concentrated on roof insulation, windows, air-tightness and ventilation but avoided upgrading the existing walls. This delivered energy performance far better than a new-build home with little risk of unintended condensation.
This approach also means there is plenty of clean, fresh air 365 days of the year.
Which materials work best in a retrofit of an older building?
Natural or hygroscopic insulations / materials:
These are very useful in retrofits of older buildings. They help reduce the risk of interstitial condensation and mould growth by allowing moisture to pass through. Materials include wood-fibre insulation; hemp/lime plasters or insulation; and clay plasters.
From our experience on Cinder Bridge Road we found the hemp/lime plaster applied to the existing walls made a huge difference to humidity levels in the house. This vastly improved comfort and, despite its minimal insulation, instances of condensation have disappeared.
new and old at cinder bridge road
Intelligent/directional vapour control membranes:
These are great at improving air-tightness whilst also protecting the building’s construction. They typically work by allowing vapour to escape the construction when required. Alternatively they can control the way in which moisture can pass through a structure.
There is a risk with non-intelligent vapour membranes that moisture can be trapped inside the construction causing serious damage.
At Sycamore Hall we used an intelligent membrane with a simple internal wall insulation to dramatically improve our clients comfort whilst minimising risks. This was combined with a well-designed and installed MVHR system to deliver a comfortable and risk-free build
Are you ready to improve the performance of your historic home?
As a practice we’re passionate about improving the comfort, safety and health of our clients by retrofitting their homes or businesses.
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