Optimal thermal control technologies for public spaces

Public spaces are integral to urban architecture and aesthetics, fostering social connections and providing comfort in bustling cities. Outdoor thermal comfort within these spaces is influenced by various factors, making it a multifaceted consideration. Industry experts suggest various innovative methods ranging from ancestral to modern methods for natural thermal cooling.

“Thermal comfort is not just about maintaining a certain temperature, but about creating an environment that promotes well-being.”

Public spaces are designed for open access to the public, except for venues with entrance fees like auditoriums. These areas, such as airports, railway stations, and community centres, typically rely on mechanical cooling and ventilation systems. Given the pressing issues of energy consumption, energy efficiency, and the need for decarbonisation, exploring innovative cooling methods for these spaces is crucial. Some options include evaporative cooling in dry, low-humidity regions, single-stage and two-stage systems, and the adoption of radiant cooling from surfaces like floors and ceilings, significantly reducing the cooling requirements. Another viable approach is displacement ventilation, which can help lower the cooling demands in public spaces.

However, beyond energy considerations, ensuring indoor air quality and safety is paramount in public spaces. It is essential that anyone entering these areas remains safe during their stay and when exiting. To address this concern, there’s a growing emphasis on improving air quality by enhancing filtration, increasing the rate of air changes, and monitoring contamination levels within public spaces in India.

Approaches to enhance public comfort
Numerous emerging technologies aim to enhance comfort in public spaces, but widespread adoption remains challenging. Pursuing better thermal comfort in these areas involves scientific analysis and research. To address this challenge, a system modelling approach is being considered. With energy efficiency, sustainability, and decarbonisation taking centre stage, it is important to recognise that public spaces are vast, and the occupants’ activities are often dynamic and ill-defined, changing over time.

Two predominant approaches are typically followed in designing and evaluating these spaces. The first is the prescriptive method, which employs heuristic rules based on occupants’ number and activities. This approach is commonly used in the industry. The second is the performance-based method, which involves creating comprehensive models to determine the optimal conditions for each individual within the public space.

The industry is moving toward the performance-based method, which aims to harness technology developed over the past two decades by organisations like the Department of Energy. Mr. Sandip Jadhav, Co-Founder & CEO, CCTech noted that the ASHRAE building performance conference, held in Austin, emphasised how these technologies could be leveraged to enhance public spaces. However, there is still work to be done to build awareness and fully integrate these technologies into available infrastructure.

Challenges in integrated building design
Mr. Vikram Murthy, Director, Univac Environment Systems, shares, “The effective integration of these technologies is best achieved when architects and designers collaborate from the project’s inception. This integrated approach to building design is crucial and is increasingly emphasised, particularly in planning large structures such as airports and public spaces like the new Parliament House. These collaborative efforts face several challenges.”

First, the need for ample space to accommodate the various components for optimal performance is a significant challenge. This includes the size of equipment, ductwork, and return air spaces. Often, space constraints become a point of contention between architects and designers. Second, ensuring a high-quality installation is another key challenge. Regardless of a well-conceived design, poor installation can lead to long-term issues. Even the best intentions will not yield the desired results if the installation is subpar. The third challenge involves proper client training for operating the systems. A building’s performance over its 15 to 20-year lifespan depends on how it is operated. Therefore, architects must ensure clients are equipped to manage the building effectively.

Building system challenges
Designers face numerous challenges when working on building systems. It’s a complex task, much like designing phone operating systems, where extensive resources are invested in simulating, analysing, and optimising various aspects. However, buildings are typically designed only once, making it challenging to allocate significant resources for this purpose. Mr Jadhav notes that the cost of designing and optimising for factors like indoor air quality is a substantial hurdle.

Additionally, the physics involved in building systems design are intricate, involving fluid flow, thermal considerations, air filtration, and CO2 levels, among other factors. These complexities make it a challenge even for experts. The air distribution system and elements like glass type, window configurations, and flooring materials determine the impact on occupants. Designers need access to a robust and affordable toolset to address these issues effectively.

Another challenge is meeting building code compliance, as designers must adhere to these regulations while striving to create a comfortable environment for building occupants. The conventional approach often presumes that people are comfortable and rely on thermostats to maintain this comfort, which can be oversimplified and problematic.

Building maintenance
According to Mr. Jeelani Pasha, Regional Manager, South of Trane Technologies India, there are three critical aspects to consider in the realm of building systems: design by architects, implementation, and maintenance. While systems can be meticulously designed and implemented at a high initial cost, these systems must continue to function effectively over the building’s entire lifecycle, which may span 15 years or more. This necessitates a strong focus on maintenance, and those responsible for maintaining these systems must possess the necessary knowledge and expertise.

We often witness that compromises may be made over time after a system is initially designed and installed. It is sometimes neglected if a system underperforms after a year or two. This results in unnecessary energy wastage and compromises the overall comfort of the building’s occupants. Therefore, there should be a heightened emphasis on the ongoing maintenance of buildings to ensure both human comfort and energy efficiency are maintained throughout the building’s entire lifecycle.

Air filters
Ensuring good air quality in public spaces is crucial for social responsibility and business considerations. Deepak Puranik, National Sales Head – Strategic Business – India and Sri Lanka, AAF India, adds, “To achieve this, it’s essential to begin with awareness. This starts by measuring air quality and identifying the pollutants that affect indoor air quality, which can be particulate matter or gaseous contaminants. Addressing these issues involves implementing effective filtration systems.”

Pollutants can originate from sources within the indoor space or be introduced from outside air. The recent global crisis, COVID-19, has emphasised the importance of human well-being in indoor spaces, not only for this specific virus but also for protection against various bacteria and viruses. Several technologies are available to mitigate these risks. Electronic filters help somewhat, but the most reliable solution is HEPA filters. HEPA filters have a pore size ranging from 0.072 to 0.12 microns, while viruses are typically around 0.10 microns. By incorporating HEPA filters into the air circulation path, you can effectively block the transmission of viruses. HEPA filters, particularly H14-grade filters, operate with an efficiency of 99.995%. Upgrading to U15 or U16-grade filters increases efficiency to 99.9995% or 99.99995%, depending on the criticality level. It’s essential to consider the type and capacity of equipment for implementing HEPA filters, whether centralised in AHUs or as standalone units within public spaces.

IAQ Standards
When designing public spaces to meet optimum indoor air quality requirements, it’s important to adhere to guidelines from organisations like the WHO, WELL, or OSHA, depending on the specific standards the public place aims to follow. However, what often happens during the design phase is that indoor air quality is not given the attention it deserves. It needs to be a visible aspect of design and tends to be addressed as an afterthought or a miscellaneous factor.

Mr Puranik thinks that one significant issue is that the selection of air filters is often based on assumptions. Designers typically include pre-filters and additional filter stages to demonstrate some level of filtration. However, what’s frequently needed is the scientific approach to selecting the right grade of filter. This involves understanding which grade of pre-filter, fine filter, or HEPA filter is appropriate for the building.

Moreover, the aspect of measurement is often overlooked during the design phase. Measuring indoor air quality is sometimes considered an external element or a retrofit solution when it should be an integral part of the initial building concept. With evolving technology, equipment and systems are available that, if integrated into the design from the outset, can significantly enhance indoor air quality more effectively than when retrofitted at a later stage of construction.

Air distribution
Ensuring many people’s comfort in vast spaces like the Delhi Exhibition Center during events such as the G20 meeting is a unique challenge. In such scenarios, precision in control is essential. For smaller venues, you can often control comfort individually, but a different approach is needed in much larger public spaces like malls or airports.

In these situations, control primarily involves managing air motion (air velocity) and temperature. Achieving both of these objectives requires the use of advanced sensors to monitor temperature and humidity continuously. Moreover, it hinges on a well-thought-out air duct and distribution design. This complex science is sometimes underestimated, as people assume that simply circulating air will make everyone comfortable. However, the proper air distribution design is critical to ensure even comfort throughout these large spaces. It’s about creating an environment where people in every corner of the area feel equally comfortable.

An integrated approach that combines the building envelope, HVAC system, and control sequences is the way to achieve excellent thermal comfort. When all stakeholders collaborate to make this system work effectively, we can fulfil our objectives of reducing energy consumption, minimising climate impact, and enhancing indoor air quality. Most importantly, this approach ensures that the people in these spaces are happy and comfortable. Therefore, a holistic and collaborative approach is essential for addressing these multifaceted challenges successfully.

Vikram Murthy, Director, Univac Environment Systems Pvt. Ltd.
“Proper air distribution design is critical to ensure even comfort throughout these large spaces.”

Deepak Puranik, National Sales Head – Strategic Business – India and Sri Lanka, AAF India.
“Measuring indoor air quality is sometimes considered an external element or a retrofit solution when it should be an integral part of the initial building concept.”

Sandip Jadhav, Co-Founder & CEO, CCTech
“An integrated approach that combines the building envelope, HVAC system, and control sequences is the way forward to achieve excellent thermal comfort.”

Jeelani Pasha, Regional Manager, South of Trane Technologies India
“Those responsible for maintaining these systems must possess the necessary knowledge and expertise.”