Health and wellbeing - residentialDecember 2016
Tassos Kougionis, Principal Consultant – Residential, BSRIA Sustainable Construction Group
Designing homes for the present and the future
With an increased housing demand in the UK, government research indicates that around 200,000 new homes a year should be built to avoid a housing shortage.
There are around 27.8 million residential properties in the UK, with the majority of them constructed before 1990. According to DCLG housing statistics the number of permanent dwellings completed between 1978 and 2015 was around 7.32 million.
The houses we design and build last for decades and are the places we spend most of our time. Our health and wellbeing depends on the quality of the environment we live in, which makes it increasingly important that we consider a number of aspects when either designing new or retrofitting existing residential properties.
Built to address a number of needs, homes accommodate a variety of household and resident types with varying needs, incomes and daily routines. Climate change and changes in the urban environment add an additional layer of complexity when considering resilient home designs. Design strategies used by developers and architects today need to consider both adaptability and performance of the home in the future to deliver a product ‘fit for purpose’.
With new advanced digital performance estimation tools, innovative construction systems, new materials in the market and an increasing understanding of various issues around home construction through research, the building industry today has an inherent advantage compared to the construction industry of the past.
Building homes that consider both the present and the future can be challenging. It is commonly perceived that anything outside business as usual can lead to higher construction costs and delays in the construction process. Even though the learning curve may be steep on occasions, the rewards are not to be underestimated. Investing in robust delivery strategies and QA frameworks up front (streamlined processes) will save construction stakeholders substantial time and cost in the long run as proven by a number of exemplar projects across the country that applied such principles from the start. The process itself will advance in-house knowledge and skills, improve brand reputation and make businesses resilient to future changes in regulations.
Fig 1: Illustration of the three main causes of over heating in buildings (click image to zoom)Overheating in buildings is not easy to define. Overheating occurs when the indoor environment of a building moves from uncomfortably warm to excessively hot for the occupier. The severity of the phenomenon is usually described by the duration of exposure to higher temperatures and the intensity - how high temperatures experienced were.
Even though overheating is more likely to occur during periods of hot weather, there are other important parameters that directly affect indoor temperatures. These include:
Design and orientation of the property
Urban heat island effects
Even though careful planning and design of a building can be used to reduce the likelihood of a property to overheat, such consideration has been traditionally used mostly for non-domestic buildings and especially offices. These buildings are usually assessed with dynamic simulation tools, and offer air-conditioning or cooling options during their operation.
Emerging evidence and research study results confirm that overheating in residential properties is becoming more noticeable. With average temperatures increasing globally and a strong drive for highly energy efficient, new and retrofit residential projects overheating can pose a serious risk moving forward.
Design decisions and development strategies should be informed by latest findings around assessing overheating with specialist advice sought where appropriate.
Specific categories of the population (the very young and the elderly) are more sensitive to developing problems due to overheating.
Thermoregulation can be impaired in older people or people that suffer from chronic illness. Metabolic heat can also create problems in young children in a hot environment.
People that are the most vulnerable to extreme temperatures, such as the elderly or sick, are also the people more likely to be occupying homes for most hours.
It is very important that the property user has a way to dissipate excess heat, fast enough, when the property overheats. This is usually achieved through an appropriate ventilation strategy.
Special provisions for cooling might be required when dealing with vulnerable groups or when the likelihood of overheating is deemed high.
Ventilation and indoor air quality
Fig 2: How do we ensure a good ventilation rate and good indoor air quality? (click image to zoom)Key to our health and wellbeing is the quality of air we breathe. Appropriate indoor air quality, defined as the absence of air contaminants/pollution which may impair the comfort or health of building occupants, can reduce the chance of respiratory problems, allergies and health conditions. At the same time low air quality can increase stress levels and affect our mental health (sick building
Minimum ventilation rates, along with performance criteria for different ventilation systems, are described in Building Regulations Approved Document F. Achieving appropriate ventilation rates at home is crucial for removing pollutants and odours, controlling humidity levels and controlling hot indoor temperatures. Special provisions in regards to ventilation rates and combustion devices are described in Buildings Regulations Approved Document J.
Recent studies conducted on the performance gap between the design and as-built performance of homes highlighted issues both with fabric airtightness levels achieved on completion of units and problems with the design, installation, commissioning, operation and use of ventilation systems.