Dr. Zuhaib Batra is an architect with over 10 years of experience in built-environment design and research projects. He currently works as a Scientific Collaborator at the Smart Living Lab in Fribourg, Switzerland, and previously he also worked for more than 5 years at Buildings Performance Institute Europe as a Senior Project Manager. His work involves projects related to energy efficiency, whole life carbon, renovation and decarbonisation. With a strong background in sustainable design, nearly zero-energy buildings (nZEBs), building energy modelling, life cycle analysis and Indoor Environmental Quality, he is a skilled professional in building energy and carbon performance. He earned his Ph.D. in developing deep-retrofit decision-making support for achieving nZEBs with enhanced comfort. He is an accredited professional in green buildings from IGBC (India) and a certified professional in ‘Professional Energy Skills in nZEB’ (Ireland), and has published several articles in reputed international conferences and journals. He is the recipient of DAAD postgraduate fellowship, Science Foundation of Ireland PhD fellowship and Marie Curie European postdoc fellowship. He is also the co-author of popular reports such as Healthy Buildings Barometer 2024 and Global Status Report of Buildings and Construction 2022 (UNEP).
BUILD UP (BUP): Why is high indoor environmental quality (IEQ) important for households, and what are the implications of poor IEQ?
ZUHAIB BATRA (ZB): High indoor environmental quality (IEQ) is crucial for households because it directly impacts the health, comfort, and well-being of the occupants. Good IEQ encompasses factors such as indoor air quality, lighting, thermal, and acoustic comfort, all of which contribute to a healthy indoor living environment. The main benefits of high IEQ are:
Health benefits: High IEQ reduces the risk of respiratory issues, allergies, and other health problems. Clean air, free from pollutants and allergens, is essential for maintaining good health, especially for children, the elderly, and those with pre-existing health conditions.
Comfort and productivity: A well-regulated indoor environment enhances comfort and can improve productivity. Proper lighting and thermal conditions help create a pleasant atmosphere, making it easier for residents to relax, work, and perform daily activities efficiently.
Mental well-being: Good IEQ can positively affect mental health. Natural light, for instance, has been shown to improve mood and reduce stress levels. A quiet and comfortable indoor environment can also promote better sleep and overall mental well-being.
The key implications of poor IEQ are:
Health risks: Poor IEQ can lead to a range of health issues, including respiratory infections, asthma, and other chronic conditions. Exposure to pollutants like mould, dust, and volatile organic compounds (VOCs) can exacerbate these problems.
Reduced comfort: Inadequate lighting, poor indoor air quality, and uncomfortable temperatures can make living spaces unpleasant. This discomfort can affect daily activities and overall quality of life.
Reduced productivity: Poor IEQ can hinder concentration and productivity. For those working or studying from home, an uncomfortable environment can lead to decreased performance and increased stress.
Increased costs: Addressing health issues and discomfort caused by poor IEQ can lead to higher medical expenses and energy costs. For example, inefficient heating and cooling systems can result in higher utility bills.
BUP: What parameters contribute to the definition of indoor environmental quality?
ZB: Indoor Environmental Quality (IEQ) is a comprehensive concept that encompasses various parameters which collectively determine the quality of the indoor environment. There are four key parameters of IEQ that include:
Indoor air quality: It involves the presence of pollutants, allergens, and ventilation effectiveness. Good air quality means low levels of contaminants such as carbon dioxide (CO₂), volatile organic compounds (VOCs), and particulate matter (PM2.5/10).
Thermal comfort: It refers to maintaining an optimal temperature and humidity level that is comfortable for occupants. Factors such as air temperature, radiant temperature, humidity, and air movement all play a role in thermal comfort.
Visual comfort: Adequate and appropriate lighting, both natural and artificial, is crucial. Good lighting reduces glare, provides sufficient illumination for tasks, and supports circadian rhythms, which can affect sleep and overall well-being.
Acoustic comfort: Sound levels and acoustics impact comfort and productivity. Good IEQ includes managing noise levels to minimise distractions and disturbances and ensuring a quiet and peaceful environment.
BUP: How are energy efficiency in buildings and indoor environmental quality related?
ZB: Energy efficiency in buildings and indoor environmental quality (IEQ) are closely related and often influence each other. Maintaining high IEQ can also support energy efficiency by optimising the performance of building systems and reducing the need for excessive energy use. Balancing both aspects is key to creating sustainable and healthy living environments. A few examples to explain these relationships are:
Efficient HVAC systems are designed to consume less energy while maintaining optimal indoor temperatures and indoor air quality. Properly maintained and energy-efficient HVAC systems ensure good thermal comfort and indoor air quality, which are key components of IEQ.
Good insulation and air tightness reduce energy consumption by minimising heat loss in winter and heat gain in summer. This not only improves energy efficiency but also helps maintain consistent indoor temperatures, contributing to thermal comfort.
Energy-efficient lighting (e.g. LED bulbs) consumes less electricity and generates less heat compared to traditional lighting. This reduces the cooling load on HVAC systems and provides better lighting quality, enhancing visual comfort and overall IEQ.
Energy-efficient buildings often incorporate advanced ventilation systems that provide adequate fresh air while minimising energy use. These systems help remove indoor pollutants and maintain good air quality, which is essential for a healthy indoor environment.
The use of sustainable and low-emission building materials can improve both energy efficiency and IEQ. Materials that have low volatile organic compound (VOC) emissions contribute to better indoor air quality, while energy-efficient materials help reduce the building’s overall energy consumption.
Utilising natural ventilation and daylighting reduces the need for mechanical ventilation and artificial lighting, leading to energy savings. At the same time, these strategies improve indoor air quality and provide natural light, which can positively impact occupants' health and well-being.
BUP: What steps can we take to improve the indoor environmental quality in our homes, or how does our behaviour influence IEQ?
ZB: Improving indoor environmental quality (IEQ) in our homes involves a combination of practical steps and mindful behaviours. Enhancing ventilation is crucial; using exhaust fans in kitchens and bathrooms to remove moisture and pollutants, opening windows regularly to allow fresh air to circulate, and considering the installation of a mechanical ventilation system with heat recovery (MHVR) can significantly improve air exchange without losing energy. Maintaining HVAC systems is also important; regularly cleaning and replacing air filters, scheduling annual maintenance checks, and using air purifiers can help reduce indoor pollutants. Controlling humidity by using dehumidifiers in damp areas and maintaining indoor humidity levels between 30-50% can prevent mould growth and ensure comfort. Choosing low-emission materials, such as low-VOC paints and finishes, and selecting furniture and carpets certified for low chemical emissions can also enhance IEQ. Improving lighting by maximising natural light and using energy-efficient LED bulbs, reducing noise with rugs, curtains, and acoustic panels, and ensuring windows and doors are well-sealed to block external noise are additional steps to consider. Regular cleaning, including dusting and vacuuming, and using non-toxic cleaning products can further reduce allergens and pollutants.
Behaviour also plays a significant role in influencing IEQ. Avoiding smoking indoors prevents harmful pollutants from affecting air quality. Using range hoods or exhaust fans while cooking, keeping kitchen surfaces clean, and incorporating houseplants that help purify the air, such as spider plants, and snake plants, can improve indoor air quality. Personal habits like removing shoes at the door to prevent tracking in dirt and pollutants, storing chemicals and cleaning products properly, and regular pet care, including grooming and bathing pets and cleaning pet bedding and areas frequently, contribute to maintaining a healthy indoor environment. By taking these steps and being mindful of our daily habits, we can significantly improve the indoor environmental quality in our homes.
BUP: What regulations or standards govern IEQ and how is this theme addressed in European policies related to building energy efficiency, such as the Energy Performance of Buildings Directive?
ZB: Indoor Environmental Quality (IEQ) is governed by various regulations and standards that aim to ensure healthy and comfortable indoor environments. These guidelines are often developed by national governments, international organisations, and professional bodies. For example, the World Health Organization (WHO) provides guidelines on indoor air quality, while national standards may address specific aspects like ventilation, lighting, and acoustics. From different EU Member States, like in Germany, the IEQ levels are primarily governed by the DIN EN 15251 standard, which focuses on indoor air quality, thermal environment, lighting, and acoustics. In France, the NF EN 15251 standard is like Germany, but with additional national regulations like the Grenelle II law, which mandates regular monitoring of indoor air quality in public buildings, especially schools and nurseries. In Sweden, the IEQ standards are outlined in the Boverket Building Regulations (BBR) that include specific requirements for ventilation, moisture control, and indoor air quality. Furthermore, Italy follows similar UNI EN 15251 standard, with additional national guidelines that emphasise the importance of natural ventilation and the use of low-emission building materials.
At European level, the Energy Performance of Buildings Directive (EPBD) plays a significant role in addressing IEQ within the context of building energy efficiency. It aims to improve the energy performance of buildings across the EU, contributing to the broader goals of reducing greenhouse gas emissions and achieving a decarbonised building stock by 2050. The directive sets out minimum energy performance requirements for new and existing buildings, promotes the use of renewable energy, and encourages the renovation of the worst-performing buildings. It also emphasises the importance of maintaining good IEQ while improving energy efficiency. For instance, it supports measures to enhance air quality, thermal comfort, and lighting in buildings. The directive encourages the integration of advanced ventilation systems, the use of low-emission materials, and the implementation of smart technologies to optimise indoor conditions. By addressing both energy efficiency and IEQ, the EPBD ensures that efforts to reduce energy consumption do not compromise the health and comfort of building occupants.
BUP: What actions are recommended in these documents to achieve a higher level of indoor environmental quality?
ZB: Various standards across European countries recommend similar key actions to maintain a high level of IEQ such as adequate ventilation to provide fresh air and remove pollutants and minimise the use of materials that emit pollutants by selecting low-emission building materials and products. One of the main actions is to prevent moisture accumulation to avoid mould growth especially in colder regions through proper building design. Maintain comfortable indoor temperatures and humidity levels with proper insulation, heating, and cooling systems and ensuring adequate natural and artificial lighting to support visual comfort. Reduce noise levels with soundproofing measures and noise-absorbing materials and conduct regular inspections and maintenance of building systems to ensure they function correctly and efficiently.
The Energy Performance of Buildings Directive (EPBD) also recommends several actions to achieve a higher level of indoor environmental quality (IEQ). Enhanced ventilation systems are mandated to ensure adequate air exchange and maintain healthy indoor air quality, incorporating both mechanical and natural ventilation solutions. It also expands the scope of mandatory Building Automation and Control Systems (BACS) installation, which helps monitor and control indoor environmental parameters such as temperature, humidity, and air quality, ensuring optimal conditions for occupants. It requires Member States to set specific standards for indoor air quality, including guidelines for acceptable levels of pollutants and measures to ensure compliance.
The Smart Readiness Indicator (SRI) is introduced to assess a building's capability to adapt to the needs of occupants and the grid, enhancing both energy efficiency and IEQ. This includes the use of smart technologies to monitor and improve indoor conditions. New buildings and those undergoing major renovations must implement self-regulating temperature controls and hydronic balancing to ensure consistent and comfortable indoor temperatures while optimizing energy use.
The EPBD also emphasises the importance of continuous monitoring and regular maintenance of building systems to sustain high IEQ, including routine checks of HVAC systems, air quality, and other environmental parameters. Additionally, raising awareness among building occupants about the importance of IEQ and energy efficiency is crucial, and the directive supports educational initiatives to promote best practices and encourage behaviours that enhance indoor environments.
BUP: In your opinion, how can public awareness of indoor environmental quality be improved?
ZB: Improving public awareness of indoor environmental quality (IEQ) is essential for promoting healthier living environments and I believe there are several ways in which this could be achieved. For example, educational campaigns launched by governments and health organisations can inform the public about the importance of IEQ, including information on common indoor pollutants, their health effects, and ways to improve air quality at home. Integrating IEQ topics into school curriculums can educate children and their families about maintaining healthy indoor environments, with schools implementing practical activities like monitoring classroom air quality to engage students in real-world applications. Furthermore, hosting public workshops and seminars by local governments can provide valuable information to homeowners, tenants, and building managers on topics such as ventilation, moisture control, energy-efficient renovation and the use of low-emission materials.
Creating comprehensive online resources, such as websites and social media pages, can make information about IEQ easily accessible, offering tips, guidelines, and interactive tools to help individuals assess and improve their indoor environments. Collaborating with healthcare providers can help raise awareness about the health impacts of poor IEQ, with doctors and nurses providing patients with information on how to improve their home environments, especially for those with respiratory conditions or allergies.
Increasing media coverage on the importance of IEQ can reach a broad audience, with news articles, TV segments, and radio shows highlighting the benefits of good IEQ and sharing success stories of communities that have made improvements. Encouraging manufacturers to label products with information about their impact on IEQ can help consumers make informed choices, with labels indicating low VOC emissions, energy efficiency, and other IEQ-related attributes guiding purchasing decisions. By implementing these strategies, I am hopeful that public understanding of IEQ will increase and encourage actions that lead to better indoor environments in homes.
