Testing

/ Chris Simmonds / Places to live

Reflecting on the topical issue of whether self regulation or statutory controls are more effective in so many aspects of our life, from health to finance, from journalism to the media, it is interesting that the construction sector has been a test bed of increasing regulatory controls. Two such procedures, in the demand for air tightness in buildings to prevent unnecessary heat loss, and in the acoustic performance of domestic buildings show that increased expectations have led to an increase in construction standards and building quality across the board. Has regulation worked?

In broad terms, making buildings more airtight for energy reasons requires construction to be high quality so that no gaps are left to let the air out which is of course, a good thing. Similarly for acoustic regulation, sound travels through mass which needs dampened and through holes, which generally you don’t want in a building anyway. ‘Mind the gap’ could be said to have become a construction mantra, and it has lead to better quality control and finish.

Regarding domestic sound transmission, Scotland apparently has the second highest test requirements in Europe. This has emerged in a bid to deal with fall out from anti social neighbour behavior but has now extended to consideration of the sound insulation between rooms in an apartment due to the move towards a 24hour family culture (led by the necessity of shift working or by choice of different leisure styles). Testing was a mandatory requirement of the 2010 regulations if not using the ‘deemed to satisfy’ details but now even with standard details a sound test is required. To make things more complicated, ‘deemed to satisfy’ details have become ‘example details’ and for a belt and braces approach ‘robust details’ can be used.

Robust details are selected and tested by a company set up by the construction industry with an overseeing role of building regulations contained within section 5. Only introduced in Scotland in 2012, they provide a commercial service and monitoring role to ensure the effectiveness of the promoted constructions through performance monitoring and random spot checks.

In a bid to reduce CO2, a raft of strategies have emerged including increased insulation, control of cold bridging, heat recovery and the contribution of renewables. Amongst these, air tightness remains a cost effective way of reducing emissions. A curious fact is that older buildings were surprisingly not as bad as you might think. Newer buildings with predominantly plasterboard interiors tend to be more leaky. Looking at the issue technically, default airtightness is 10, measured in metres cubed per hour at 50 Pascal pressure, which is not that high. At airtightness levels under 5 mechanical systems are needed as there is insufficient airflow.

Our current project at Laurieston had at the design stage envisaged airtightness of 7.0 however post tender the contractor is aiming at between 4.0 and 5.0. This drive coincides with another acoustic issue, that of exterior noise in cities, forcing residents to keep windows shut and necessitating some mechanical ventilation support.

In broad terms the inclination of current policy seems to be favouring an essentially ‘passive house’ strategy in a bid to avoid renewables and their associated onerous maintenance obligations. The fabric first approach is being followed but there may be, looking forward, a limit on how much the fabric can be improved in the future, and how airtight we want our living spaces to be.

Standing back from the issues there is no question that the building industry is hugely improving the quality of its output. Perhaps other industries might benefit from looking at the potential effectiveness of well measured regulation and testing.

Impression of proposals for Laurieston, Glasgow