In the intervening years the industry has learned from the many mistakes made back in the late 1960s and early 1970s in particular. Building stock constructed since then has shown marked improvement but, as we look to design buildings that will be here for the next 50, we should not be complacent.
Buildings that are performing well now, and those currently being designed and built for the today’s climatic conditions, may become intolerable for occupants by 2068 (50 years time) unless we factor in concepts such as active cooling and associated high-energy usage. There is compelling scientific evidence that our climate is changing, and it is probable that average temperatures will increase by several degrees over the coming century.
These increases in temperature are expected to have a major impact on the indoor environment of buildings. It is essential that buildings being designed and built today are future-proofed so they can adapt to changes in external temperatures and humidity, light levels, energy usage and so on.
To be fair, the construction industry has already made significant steps towards tackling climate change through limiting the amount of carbon emitted – both in the materials used (embodied energy) and predicted energy usage – by using simulation programmes such as IES, along with BREEAM and LEED.
The energy message emphasis on heat-saving in winter using highly-insulated and airtight buildings also means there is a danger of overheating in the summer months. This presents a different challenge. CIBSE has produced quite a number of guidance documents in this respect, such as TM52 (The limits of thermal comfort: avoiding overheating in European buildings: Developed for “free-running” commercial buildings) and TM59 (Design methodology for the assessment of overheating risk in homes).
The health and wellbeing impacts of overheating (see Mona Holtkoetter’s article in October 2017 edition of Building Services News) can be significant for residents, resulting in stress, anxiety, sleep deprivation and even early deaths in heatwaves, especially in cases of vulnerable occupants.
Among the concepts now being embraced to combat these issues are highly-insulated pipework; insulated heat interface units; ventilated utility cupboards; LED lighting; and installing mechanical ventilation heat recovery units, with summer bypass and boost mode, to increase the ventilation rate when required.
Climate change is affecting how buildings will perform for occupants, both now and in the future. While overheating has emerged as a major concern, climate effects extend beyond the treatment of overheating. They also include flooding, drainage, water conservation and material durability. The CIBSE TM36: Climate Change & the Indoor Environment: Impacts & Adaptation (CIBSE, 2005) document again offers guidance and advice on these matters.
In considering the design of both commercial and residential buildings today we must address the known and anticipated challenges that lie ahead and consider, among other things, the following:
• To what extent will climate change increase the occurrence of summertime thermal discomfort and overheating in different types of buildings?
• To what extent will passive measures be able to improve summertime thermal comfort and ameliorate the increased tendency for overheating?
• How effective will different approaches to comfort cooling be?
• What are the energy-use implications of the various strategies?
While no one has all the answers, there is still a wealth of guidance freely available to all concerned in building services.