Air

What is COVID-19 signaling about building design for healthy living?

The possibility that our air-conditioned and cooled living spaces may make coronavirus comfortable and spread needs to be well understood to spur bigger changes

 
By Anumita Roychowdhury
Last Updated: Tuesday 17 March 2020

As the deadly novel coronavirus (COVID-19) takes a toll and leads to a near global lockdown, the debate about its impact on the way we live, work, and design our cities to reduce contact and increase social distances to contain the pandemic, has started.

This conversation has also quite insightfully raised questions about the way we are designing homes and office buildings and if that can aid in spreading of the scourge further.

It is not only about the hygiene and super clean indoors that, in any case, is non-negotiable and must happen under the current circumstances. But the virus is also stoking conversation on the need for designing of living spaces that allow adequate ventilation and sunlight for healthy living to contain the problem.

This connection drew my attention when I read this observation of Randeep Guelria, head and Director of All India Institute of Medical Sciences in the media recently.

While all of us are hoping that summer heat will kill this virus, Guleria observed that there was no substantive evidence on this yet as the virus was thriving in warmer countries.

But he made an additional interesting point: “If heat levels are high, people will stay indoors and switch on air conditioners. This will bring down the temperature again and give space for the virus to spread.”  

When I read his observation along with other advices from the doctors about making the rooms for isolation and quarantine in homes well-ventilated with adequate solar access, images of ill-designed and thermally uncomfortable buildings with tightly closed air conditioned spaces crowded in my mind.

This brought back the antiquated photographs of Spanish flu in social media showing sun bathing and fresh air as methods for cure. This conversation is about ventilation, sunlight and open spaces around us for healthy living to avoid ‘petri dish’ buildings and prevent health complications when viruses are set loose.

This discussion is not limited to finding trace amounts of virus in an air vent of air conditioners in cruise ships, airlines and hospital or how heating and ventilation systems can do with filters and ultra violet rays to clean the air ducts; this is much beyond this.

What is the danger? It seems over-cooled spaces can be conducive for virus survival and spread through surface contamination. We do not know much about this yet. Does this have implications for the way we are designing the buildings?

If we continue to design thermally uncomfortable buildings with poor ventilation, inadequate shading and high heat loads on the structures, number of days and hours requiring mechanical cooling or air conditioning will continue to increase.

Climate change and heat waves will worsen this. An assessment by the Centre for Science and Environment (CSE) shows how electricity consumption spirals out of control when heat index increases during summer in Delhi. While cooling can protect under extreme heat conditions, it also has other health and energy security concerns. COVID-19 is reminding us that.

Most Indian homes are naturally ventilated in which people can control wind and sun with windows, openings and shading. When these are shut off to make the air conditioners work, rates of building ventilation with outdoor air gets reduced.

Closed windows in naturally ventilated buildings increase the indoor air concentrations, pollutants and the air conditioning system itself becomes sources of microbial contaminants. 

The logic seems simple — if we do not design buildings for improved thermal comfort and to reduce the air-conditioned hours, higher dependence on excessive cooling can create another trap for us — safe havens for deadly viruses. If the scientific community is already talking about this, this needs further investigation.

Thermal comfort standards for overall well-being

Let us take this health emergency as an opportunity to rethink our built environment. It is time to seriously operationalise thermal comfort standards in buildings that India’s Cooling Action Plan has asked for.

Design spaces to reduce heat load on the built structures and improve thermal comfort.

This approach goes much beyond the narrow scope of only adopting energy-efficient technologies and insulation systems. It includes a broader comprehensive combination of urban planning, architectural design and technology to enhance the hours and days of thermal comfort in a year to reduce dependence on mechanical cooling. India’s diverse climatic conditions allow that flexibility and opportunity.

It is possible to reduce the use of air conditioners if the building is designed to take advantage of the microclimates to be comfortable. Construction of affordable mass housing is underway across states.

But these new structures are not designed for thermal comfort, and are heat trappers with high thermal transmittance. They directly absorb outside heat and increase thermal load and increase cooling requirements.

We need interventions and guidelines / codes to promote material with slower rate of thermal transmittance, allow better night purge — when the building can lose heat quickly due to cooler air — and adopt passive designs to give people greater control over ventilation, shading and access to sun. Promote adaptive comfort that we have demonstrated in warmer indoors than what cooling industry is marketing.

This can be illustrated. Recently, we at CSE looked at the ‘third skin’ of the building and carried out analysis of some of the thermal comfort parameters in mass housing in Telangana. The team checked adherence to Eco-Niwas Samhita 2018 (Energy Conservation Building Code or ECBR-R) — the code for residential buildings.

The analysis considered some of the key parameters that have a bearing on thermal comfort including visual light transmittance, window opening to floor area ratio according to ECBC residential 2018, residential envelope transmission value, day-lit area according to National Building Code of India 2016 and annual thermal comfort using whole building energy and thermal simulation as well as comfort standard according to National Building Code (NBC) 2016.

Thermal comfort analysis considered parameters such as when outside temperature is between 18°C and 36°C; indoor temperature is higher than outdoor temperature; night time during summers, and maximum air changes per hour etc.

This tried to find out the annual percentage of thermally comfortable hours in a year in these structures and in that microclimate. Overall, it seems these dwelling units in existing design can achieve thermal comfort for a minimum of 74 per cent of the period annually to a maximum of 85 per cent.

There is variation in results according to orientation, aspects, floor level etc. This can help to decide design and orientation options. For instance, if only heat ingress (expressed as residential envelope transmission value) is considered, north-south oriented buildings showed the lowest value.

Dwelling units facing south-east and south-west directions have worst thermal comfort as these facades are exposed to direct solar radiation for longer duration than east and west. This variability can inform the orientation choices.   

Similarly, how much daylight do these buildings get? Daylight simulation according to daylight factor requirement of NBC 2016 shows that the day-lit area is 47 per cent of the total living area when other buildings are not shading the buildings.

Where the buildings are mutually shading each other, day-lit area is only 15 per cent. This has a huge implication for spatial planning and orientation of the mass housing. It therefore makes sense to have orientation norms.

For example, allow all dwelling units to get minimum two-hour solar access in at least one habitable area on the shortest winter day (winter solstice); set norms for orientation, depth of the building, shading, day lighting among others to improve comfort levels. These examples illustrate how design solutions are needed to cut heat load on buildings to reduce need for mechanical cooling.

Getting this done on the ground may still be a challenge. A study carried out by Future Foundation shows that the land use is skewed towards providing more and more housing, without adequate provision of open spaces.

This industry survey finds that if design provisions are made for more daylight penetration in affordable housing for instance, costs become unaffordable. There is also limited awareness about design solutions according to climatic and micro-climatic zones. This will have to change.

Make the connection - be virus wise

This conversation on the connection between cooled built spaces and virus spread is still nebulous. But this certainly signals that the knowledge of virology has to inform designing and use of safe built spaces to contain the pandemic.

Did we ever consciously think before how our air-conditioned comfort can also make coronavirus comfortable to thrive in our own living spaces? Let this public health crisis deepen this understanding and spur change for energy and health security. 

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