It was great to see Passive House and Retrofit finally getting on the telly yesterday in Guy Martins Home without bills on Channel 4. It is a really complicated subject that the programme managed to communicate well and with just enough detail. It was pretty much the first time that I have managed to watch a build programme without constantly shouting at the telly in frustration. Hopefully this will raise awareness of Passive House and retrofit. It certainly made the point well about the importance of airtightness and a requirement for attention to detail in both the design and on site. The Passive House Trust is following up with some free webinars for those that want further information on the subject.

Thanks to XP Surveys for the opportunity of presenting as part of your quarterly networking event in Henley. Retrofit of buildings is a massive subject but hopefully the importance of independent survey assessments, robust design using appropriate materials and a whole house approach was made. The industry needs to step away from installer lead assessments and ‘design’. Also a good opportunity to plug the AECB – Association for Environment Conscious Building and their retrofit standards.

The BBC reported today (see below) on what many in the retrofit industry have known for some time. The results of installing inappropriate insulation in unsuitable buildings, particularly as individual measures can be severe. The industry is often driven by installation companies and the people involved with assessing buildings, even under PAS2035 are often poorly qualified or experienced.

The article demonstrates the need to have independent experts involved in retrofit who have a genuine understanding of buildings types, building pathology and building physics. Those involved in retrofit must take a whole house risk based approach rather than complete tick box exercises before handing over to an insulation installer.

‘Serious and systemic’ problems found in insulated homes

Thanks to RIBA South Conservation Group and the Guildford Society for a fascinating tour of some of Guildfords historic buildings. I have lived in Guildford on and off since 1978 but still visited some for the first time. Great to hear how these historic buildings are being maintained and repaired with an eye on trying to reduce heating costs and carbon footprint where possible.

Clifford Design have been advising self builders and You Tubers ‘The Restoration Couple’ with their mammoth barn self build. Keen to get the detail right and reduce thermal bridges along the perimeter of the wall/floor junction Clifford Design suggested the use of Marmox Thermoblock. It has proven to be simple to install and will help reduce the risk of a cold strip at the base of the wall. Thermal bridges become more important to address the better the insulation is in a house. Any remaining cold spots attract moisture in the form of condensation if they fall below the dew point leading to a risk of mould growth.

We promote the use of natural materials where practicable as there are advantages for the environment and health as well as building fabric. For older buildings the use of natural materials is even more important as they work in harmony with the existing building fabric in the way they manage moisture and have a much lower risk of causing damage to the building fabric. Modern man made materials such as foam insulation and concrete render can trap moisture in the buildings fabric as they are impermeable to water vapour and liquid water. In contrast wood fibre and other natural insulation products allow the passage of water vapour and also liquid water as does lime mortar and render.

There are instances where it is not always possible to use natural insulation materials, such as below ground. XPS insulation is often used below ground as it does not absorb water and is a high performing insulator.

Clifford Design have been working with Architect Nicola Westbury to upgrade the thermal performance and also extend her own C17 Grade 2 listed home in Surrey. Nicola is a Society for the Protection of Ancient Buildings scholar who specialises in historic buildings conservation.

Retrofit of historic buildings requires a specialist approach with an understanding of suitability of materials and construction techniques. Repair, maintenance and removal of inappropriate materials is always the starting point, then a light touch retrofit using natural materials so as not to risk damage to either the fabric of the building or its historical significance.

Any works to listed buildings beyond maintenance and like for like repair require listed building consent.

A full property assessment was undertaken including thermal imaging survey combined with an air leakage pressure test as well as a Heritage impact risk assesment. Interestingly in the air leakage test the C17 buildings performance was far higher than standard assumptions and similar to many properties built in the 1990’s. Examining all of the fabric elements allowed more accurate values to be used in a PHPP heat loss model. The PHPP model was then used to test a number of improvement options that were also evaluated for their risk to the building fabric and its historical significance.

A cold snap is the perfect time for a thermal imaging survey, and it has been down to -8 this week in Surrey. A Thermal Imaging survey as part of a whole house retrofit assessment can identify problem areas for thermal bridging as well as highlight missing or badly fitted insulation. The resulting pictures are clear for clients to understand just how important it is to have continuous insulation wrapping their home, and just how much heat can be leaked through poor detailing and thermal bridging.

Blower door test and Thermal Imaging

When a thermal imaging survey is combined with a blower door pressure test an extra layer of information is uncovered. The house is depressurised with a fan at the front door, allowing cold air from outside to infiltrate that can be seen with the camera.

Sustainable Design in Housing,

Addressing the Climate and Energy Crisis.

It was great to be given the opportunity to present along side Justin Bere at the 2022 Architecture Lecture for the Guildford Society in conjunction with the University of surrey.

The video below is a recording of the presentation of my own self build project and also taking a look at low energy housing locally.