Materials testing
New techniques and materials aimed at producing low carbon solutions mean this is an exciting time to be involved with new build and retrofit. There are dangers though, in the rush to innovate there may be failures along the way so it’s vital that there’s scrupulously testing and monitoring at all stages. This is why I was excited to hear about The HIVE, a new construction materials test facility at the BRE Centre for Innovative Construction Materials at the University of Bath’s Building Research Park in Swindon.
The £1m HIVE is funded by the Engineering and Physical Sciences Research Council. The building has eight individual cells constructed to be completely insulated from one another, each with a single face left exposed to the external environment. Within these faces walls can be installed that are made from a whole range of materials and construction systems. Importantly, the performance of these walls can then be evaluated in realistic, real life, open-air conditions. Consequently this creates a more accurate picture of environmental performance than the U-value assessments currently used in building regulations.
Real life testing is important. We’ve already seen the value of this in understanding appropriate retrofit solutions. Results from the Society for the Protection of Ancient Building’s (SPAB) in-situ monitoring of existing solid walls have shown that certain construction types perform much better in reality than their expected, theoretically calculated U-values. This is because standard U-value calculation programmes were designed to simulate modern materials such as bricks which are largely predictable. Calculated U-values do not necessarily take account of less uniform construction. For example, rubble-stone walls (which are constructed with random-sized stones) contain large air voids, lumps of earth and lime-based mortars which improve the insulation qualities of the wall. Likewise wattle and daub is a better insulator than is theoretically assumed.
In retrofit situations we’re still trying to understand how different materials will work for different applications and, even where the materials are proven, we’re often relying on high standards of workmanship to ensure they function as intended. Worryingly, without careful monitoring, potentially failures might not be obvious for some years and, in the meantime, both the health of the building and its occupants may be suffering.
Even where we think we know how a building will perform we mustn’t relax. I’ve recently visited new build homes that, on paper, seemed to work but overheating has occurred due to the way the occupants are using the buildings. I’ve also seen mould on walls and ceilings because ventilation systems have been turned off by residents trying to cut their electricity bills.
Image: ©University of Bath