Net zero retrofit and the indoor environment: the Glasgow Tenements case study

In 2019, the UK became the first country to declare Climate Emergency. Since then, policies have focused on achieving legally binding net-zero targets. With the worst-performing building environment in Europe, the UK has targeted the housing sector. While these policies are important to the environment, some of the changes we made to existing homes are not fully understood. This work presents indoor environmental monitoring (temperature, relative humidity and carbon dioxide) of a tenement in Glasgow retrofitted to the enerPHit standard.

The environmental analysis suggests that the temperature (67% of the time), relative humidity (75% of the time) and CO2 (100% of the time) were within the recommended parameters. Overheating as defined by the Passive House Institute (>25°C in more than 10% of the time) was only observed in 1 of the 7 monitored dwellings. The same dwelling also had a higher occurrence of relative humidity below 40%RH. This project showcases the potential to preserve Glasgow's magnificent stone heritage while creating flats requiring less heating than newly constructed equivalents, thanks to natural, low embodied materials.

While retrofit measures can help to reduce the energy consumption significantly - to 25.9 kWh/m2/year in this case (~90% lower than that of a similar), it is important to understand the indoor environmental conditions, as these can lead to increased performance gaps. Moreover, with the increased number of hospitalisation due to poor housing conditions, particularly mould, in the UK, indoor environment conditions have become a pressing matter.