90% Indoors: The Search for Healthy Building Solutions

As a means to tackle climate change and increase energy security, improving the energy efficiency of buildings is well established on the EU policy agenda. But the requirement to create ‘healthy’ buildings, which enhance the comfort and well-being of inhabitants, receives far less attention. New research shows how natural eco-building materials are uniquely capable of delivering on both fronts.

The buildings sector is one of the most resource hungry in the EU, accounting for the largest share of total final energy consumption (at around 40%) and 35% of all CO2 emissions. Therefore, switching to more energy efficient methods of construction will be key transitioning to a low-carbon society. Recognizing this, in 2010 the EU started to regulate the energy performance of new and renovated buildings.

Buildings must be more than simply energy efficient of course. As we spend up to 90% of our time indoors, buildings and the environment they create also have a significant impact on our comfort, well-being and even health. This has led to growing calls for the integration of ‘healthy’ principles into building design and construction, paying more attention to factors such as thermal comfort, air quality, light and noise.

Breathing Fresh Air

The health implications of indoor air quality in particular are highlighted by a growing body of research. Amazingly, indoor air is on average 2 to 5 times more polluted than outdoor air, and some common indoor pollutants like volatile organic compounds (VOCs) – those chemicals released by cleaning products, furniture and paints – have been found to cause headaches and irritate eyes and skin. Issues related to humidity also have serious health implications: the presence of damp and mould almost doubles the risk of asthma or respiratory problems.

As we spend up to 90% of our time indoors, buildings have a significant impact on our comfort, well-being and health.

However, combining these considerations to create healthy and energy efficient buildings is not always straightforward. In fact, modern energy efficient building methods have been known to worsen rather than improve indoor air quality. By aiming for greater air tightness in order to reduce heat losses and gains, these buildings are often reliant on mechanical ventilation systems to bring in fresh air. If these systems are not properly used or maintained a build-up of harmful gases can occur.

Breakthrough eco-building solutions

One solution is to build with natural materials, which are known to have a positive impact on indoor environmental quality. Natural materials, like clay and timber, have been used since time immemorial, but are relatively niche in today’s construction industry, unable to compete with mass produced concrete and steel. The EU funded research project ECO-SEE set out to bring natural materials back into mainstream use by showing how their unique qualities make them the ideal solution for modern challenges of energy efficiency and indoor air quality.

The project characterized 21 different natural materials in the laboratory, testing how they influence air quality and humidity. The most promising materials were selected for further development to create new building products for insulation, coatings and panels.

Amazingly, indoor air is on average 2 to 5 times more polluted than outdoor air.

Bio-based insulation from sheep’s wool, hemp and recycled paper can already compete with conventional products in terms of thermal performance. And being non-toxic they are also much easier to handle and recycle. ECO-SEE modified and enhanced these materials to enable them to also capture VOCs, substantially improving indoor air quality.

A novel clay plaster has also been developed during the project which helps minimize problems related to humidity. Clay is hygrothermal and vapour permeable, meaning that it is ‘breathable’, naturally absorbing and releasing moisture to maintain a safe and comfortable humidity level. Keeping relative humidity at a moderate level – between 30-60% – reduces related health problems dramatically.

ECO-SEE has also investigated new methods to enhance the power of nature. Partners have produced an innovative photocatalytic coating, using the same nanotechnology as self-cleaning walls or windows. This coating, which is light-activated and tailored to specific application onto timber and lime based internal surfaces, cleans air by removing pollutants like VOCs.

Multiple benefits of natural materials

To enable the symbiotic use of these eco-materials, ECO-SEE partners have created internal partition and external highly insulated wall panels incorporating the new solutions. The performance of these wall panels have been evaluated at demonstration sites in the UK and Spain. Testing is still ongoing, but already the levels of harmful gases and contaminants are lower in the ECO-SEE demo building compared to the reference.

Results have also highlighted the exceptional energy performance of natural materials, with the external panel 50% better than reference materials. And it is not only in terms of their operating performance that these materials are extremely energy efficient. Like almost all natural construction materials their embodied energy – the amount needed for their production – is also very low, 20% below reference materials.

Change on the horizon?

Despite their obvious advantages, the market for natural construction materials remains niche. However, people are starting to recognize the large gains to be made through building healthy. In one office redesign, improving indoor air quality was shown to increase productivity by 10%, in another sick days were reduced by two thirds. Studies of healthy school buildings have found children performing up to 15% better. Considering the overall cost to society of unhealthy buildings – in terms of healthcare, sick days and lower productivity – the case for eco-building solutions like those developed by ECO-SEE becomes even more urgent.

The ECO-SEE project has developed breakthrough eco-building solutions to improve the indoor environment of energy efficient buildings. Coordinated by the University of Bath, it brings together a multi-disciplinary team of researchers from universities and research organizations with a number of large enterprises and innovative SMEs whose combined expertise and capacity will lead to the commercial development of the products. Having successfully tested and validated the new solutions at locations in Spain and the UK, the project will draw to a close in August 2017.