What’s different about Sympathetic Retrofit to a standard refurbishment?

Building regulations have increased the performance of our homes over the last 50yrs. This has been an important development. The way we use our homes has changed drastically over the last 100yrs and building regulations reflect our improved building technologies, techniques and materials.

It’s about time we recognised this change and made our homes perform in the way we want them to.

Fabric First

We use a “fabric first” approach to Retrofit. This means that we analyse the building and suggest the best ways to improve the energy efficiency, starting with the building fabric. i.e. the walls, floors, roof and doors and windows. New boilers, solar panels and ventilation systems have their place, but getting the building right is the first priority.

Build Tight, Ventilate Right

By using insulation and making a building air tight, we change the way it performs, smoothing out the ups and downs of heat and comfort caused by our daily lives.

Building regulations are only just catching up with the importance of air tightness. This is the idea that you make the property draught proof when you’re refurbishing it. It’s as important as good insulation. In fact if the insulation is installed incorrectly or the draughts aren’t taken care of, a lot of the benefit of insulation can be lost.


Ventilation is a key factor in every home. In older homes there is a lot of natural ventilation, more appropriately called infiltration.

Many older homes were purposefully built with natural infiltration in mind. Our homes were heated by fires in large fireplaces, which required lots of air to burn the wood or coal in the grate.

Air was sucked up the chimney and fresh air came into the rooms to replace it.

When we switched to central heating during the 60’s, 70’s and 80’s we created a problem which we are only just starting to tackle. Central heating works by sending hot water to radiators which heat the air in the house.

But because our older homes were built with air infiltration in mind this now heated air was replaced by cold outside air. As soon as the central heating goes off, the heat goes out.

Thermal Envelope

A lot of builders are still using traditional building techniques This leave our homes cold when the heating is off. Even with improved building regulations our homes are still too draughty.

It’s not as easy as putting rigid insulation on every surface; putting the right material, in the right place is more important than trying to squeeze 150mm of insulated plasterboard into a tiny box room.

Building from the ground up is more straightforward; the layout and structure can work together to give the building a good thermal envelope. Retrofitting an existing building is more complex. The walls and floors that are already there can create thermal bridges, cavities in walls can cause thermal bypass which reduces the effectiveness of the insulation.

Moisture control

By controlling the air we take in, we can control heat loss and comfort much more easily.

We create a huge amount of water vapour just going about our daily business. Washing clothes, cooking, bathing and showering; even perspiration adds to the amount of water vapour in the air around us.

Air should be between 45%-65% for us to feel comfortable. Closing all the free infiltration can lead to high levels of humidity. There are two types of humidity, absolute and relative. Absolute humidity is the actual amount of water vapour present in a specific amount of air. Relative humidity represents how saturated the air is at a given temperature. Warm air can hold more water vapour than cold air, so cold air coming into a house will lower the overall relative humidity, but warm air going out will increase in relative humidity, just because it gets colder. When warm air cools the water vapour condenses into water droplets. This also happens when warm air hits cold surfaces, a major cause of mould in buildings.

Installing correct ventilation, and using building techniques which minimise unwanted air flow and reduces cold surfaces are two of the most important aspects of a good retrofit. This sets the approach apart from standard building techniques. I find it atrocious that many new buildings suffer from the same problems we’ve had for a hundred years when there is knowledge and experience out there able to improve the situation.


The materials that we use are also of great importance. There are a wide variety of types of insulation and building material, which have differing benefits and associated problems. A lot of the more recent products are made chemicals derived from the fossil fuel industry. If our aim is to lower our overall carbon emissions filling our houses with these types of materials is only slightly beneficial. It is much better to use materials that have come from better sources.

Wood fibre is a great material and there are other types of insulation that come from recycled plastics. These materials have their role in a considered retrofit.

Can Retrofit Save the Planet?

Not without a concerted effort from the construction industry, the government and homeowners.

But it can go a long way to improving the homes we have and reducing the carbon emissions we all produce.

Until building regulations and building practises catch up with a process that should be standard we will continue to champion the fabric first sympathetic retrofit approach.