The housing sector has traditionally been very much focused on the impacts associated with under heating our homes, the rising costs of energy, the subsequent challenges faced by millions of households falling into fuel poverty and the detrimental effects this has on people’s health and well-being. Looking at the polar opposite to this, however, and taking on board the scientist’s predictions in regard to climate change and global warming - the housing sector has another challenge to overcome. As with under heating a home, excess heat is also identified as a hazard and is included with the ‘Housing Health and Safety Rating System’.
The Problem of Overheating
There is growing evidence of widespread overheating in homes, particularly for homes built to satisfy more demanding standards of energy efficiency and airtightness. For many homes, overheating, and the discomfort it causes, may not only be limited to those rare heat waves we experience in the UK. In 2003 the summer heatwave caused the death of 2000 people in the UK. Temperatures were peaking between 26 and 37˚C and, significantly, night temperatures were staying above 19˚C.
The term overheating is used to describe when conditions in a building make occupants feel uncomfortable or stressed. The causes of overheating are often complex and not a simple measure of maximum temperature or people having their thermostat set too high.
The design guidance followed for newbuilds aims to minimise heat discomfort in buildings. For homes, the CIBSE Environmental Design Guide sets out guideline temperature thresholds - notably 28˚C for living rooms and 26˚C for bedrooms. It also defines overheating as when these temperatures are exceeded for more than 1% of the time. Looking at temperatures recorded in existing homes we know that overheating can significantly exceed these limits as it did during the summer of 2003.
The Danger to Residents
As the trend continues, and the average temperature in the UK is increasing and set to continue, the latest climate change projections show a typical increase in average summer maximum temperatures of between 2 and 4˚C by 2050. With further predictions of this increasing by 10˚C by 2080. Hotter summers in the UK are now considered inevitable, regardless of what we are doing now to tackle carbon emissions. With average temperatures set to increase, and more hot spells anticipated, overheating will undoubtedly become more commonplace in the future. So too claims under the Fitness for Habitation legislation are likely to increase as people feel uncomfortable or stressed within their homes or worse still it affects their health.
Residents who are traditionally the most vulnerable to overheating, such as the elderly are more likely to be occupying their homes for longer for this reason, in particular, our housing stock must be a key focus for concern on the risks associated with overheating.
The key factor here is not just to understand which homes are affected currently by overheating, but which homes in the future will be at risk of overheating as a result in increased global temperatures resulting from climate change. A proactive approach is required to stay compliant and to resolve this issue. The challenge the sector has to overcome is how to manage this risk and identify which homes will be at risk in the future. In the same way as we have identified homes susceptible to flooding, we need to apply the same mindset to homes susceptible to Excess Heat. Understanding how our assets are performing is critical, so is understanding the effectiveness of a range of remedial solutions to be deployed and assessed, both individually and when combined in a whole house retrofit approach. In this way, a solution can be identified that is appropriate for an individual home, which may differ significantly from the appropriate solution for the property next door due to it having south-facing windows, for example.
The IoT Data Solution
This is where real-time data and analytics can play its part. Cost-effective, IoT sensor technology and real-time data and analytics could be the answer to understanding how homes are being affected by rising temperatures. Utilising light, motion, temperature, air pressure and humidity sensors (as in the case of Switchee) along with the local weather station data can provide data-points for predicting the impact of rising outdoor temperatures. Furthermore, smart IoT devices like Switchee can actively monitor the effectiveness of remedial measures deployed to overcome overheating, in very much the same way as Switchee is extensively used to validate the effectiveness of insulation to understand heat loss.
Internal heat gains can vary depending on the type or age of the home. For newer homes, which are more airtight and better insulated, heat gain from internal sources may have a significant effect. Commonly these arise from the following:
- Occupants - This is especially relevant in homes subject to over-occupancy which can be common in affordable housing.
- Mechanical ventilation and hot water systems - These contribute significantly to heat gains. Our analytics has, for example, successfully identified where overheating has been caused by inadequate or missing insulation of community heating pipes in apartment blocks and where telecare comms equipment located within a cupboard has transferred heat into the adjoining flat within a sheltered housing scheme subsequently affecting the comfort for the resident.
- Ventilation - Sometimes heat can build up because of the ventilation design or its incorrect use by the resident. Simply not being able to open windows wide enough to provide natural ventilation can add to the problem. This, in turn, poses another issue in terms of Fitness for Human Habitation.
- Lighting and Appliances - Electrical equipment can add to heat gains as can kitchen appliances and other electrical goods such as computers. All of which radiate heat thereby exacerbating the problem within the home.
It’s clear that overheating is caused by a variety of factors, and is predicted to be more commonplace in the future. Tackling it requires an approach that can be implemented efficiently and cost-effectively at scale. It also needs to be dealt with taking into consideration the individual home. It is complemented with timely communication and behavioural change advice to residents in real-time.