Thermally uncomfortable mass housing can stop India’s National Cooling Action Plan from achieving its target

Too Hot - Photo By Suman Munshi , Perth Zoo
Too Hot - Photo By Suman Munshi , Perth Zoo

Thermally uncomfortable mass housing can stop India’s National Cooling Action Plan from achieving its target of reducing cooling energy need by 20-40 percent by 2037-38

Ensuring thermal comfort in mass housing, therefore, must be a part of the post-coronavirus outbreak ‘green’ recovery strategy: CSE

A new assessment by Centre for Science and Environment (CSE) bears out the dangers of ignoring the need for thermal comfort in mass housing and neglecting linking fiscal strategy to improve thermal comfort performance – something that must be a part of the new post-pandemicgreen recovery agenda.   

Releasing the assessment here today at a webinar and online round table meet, AnumitaRoychowdhury, CSE’s executive director-research and advocacypointed out: “According to real estate industry estimates, about 1-1.2 million dwelling units are likely to get added to the formal housing stock over the next few years. Not linking the current fiscal support strategy with mandated improvement in thermal comfort in buildings can delay thermal comfort measures and lock in enormous energy inefficiency during the operational phase of buildings.”

Added Rajneesh Sareen, programme director, Sustainable Buildings and Habitat programme, CSE: “This can compromise India’s Cooling Action Plan target of reducing cooling demand by 25-30 per cent and cooling energy requirement by 20-40 per cent by 2037-38. According to the Bureau of Energy Efficiency, energy demand in buildings can be cut down by up to 40 per cent by designing an efficient envelope.

The CSE assessment contends that the COVID-19 pandemic has reinforced the need to look at housing layouts, building design and choice of materials for addressing thermal comfort, improving liveability and reducing disease burden in our homes. All the verticals under the Pradhan MantriAwasYojana (PMAY) need to address this — including the Affordable Rental Housing Complexes that has been added as the fifth vertical by the Union Ministry of Housing and Urban Affairs. This requires mandatory provisions of thermal performance requirements in mass housing.

Key highlights of the assessment

Speed of construction and influx of new walling material

As the mass construction of housing is being scaled up under PMAY, speed of construction is becoming one of the accelerators. This is leading to influx of new material and technologies that are largely pre-fabricated and manufactured. Even though their market penetration is still not that extensive and are expensive, these are preferred for the reasons of ease and speed of construction, overall time and labour cost savings, reduced burden of loan repayment etc. The new material technologies largely utilise poured concrete where formwork can be quickly placed for construction.

It is estimated that precast can save upto 50 per cent of the time of construction. For instance, if the cost of constructing wall panel of burnt brick is about Rs80-90 per cubic feet, then that of pre-cast concrete wall can be close to Rs 400 per cu ft. And monolithic concrete wall using aluminum and plastic formwork can be at least 22.5 per cent higher based on the schedule of rates. This percentage also varies from state to state.

Speed and ease of construction may compromise thermal comfort: If the thermal properties of new materials are not assessed before adoption mass housing can become heat trappers and increase demand for energy intensive mechanical cooling. Some of these new generation materials may be good for fast construction but may not be thermally comfortable. For instance, cement massing or the thickness of these pre fabricated form structures may not be adequate and allow a lot more heat ingress. Concrete-based walling technologies might not have sufficient wall thickness to achieve the desired thermal resistance and hence, allow more heat ingress.

It is estimated that monolithic wall panel made of poured concrete with thickness of 100mm wall can have thermal transmittance value that determines the heat gain in the building – at 60 per cent higher than the conventional brick wall. This demands benchmarks, toolkits and guidance along with mandate to influence walling assembly approaches, insulation layers, shading and orientation approaches.    

Says Sareen: “CSE’s assessment of the new buildings design of affordable housing in selected sites in Telangana shows that the same design when simulated with AAC block with 150-mm thickness,leads to a gain of about 150-160 thermally comfortable hours annually over the base case of wall made of concrete of 150-mm thickness. The gain in thermally comfortable period increases dramatically to 272 hours when AAC blocks of 250mm thickness are used with proper window shading. Thus, mass housing needs a mandate and benchmark for materials and design (orientation, shading and building geometry) for thermal comfort and to reduce air conditioned hours. This requires guidance on orientation, surface exposure and shading devices.”

Link fiscal support with thermal performance 

Extensive fiscal support is being provided under the PMAYfor affordable mass housing. The government has reduced taxes, GST has been lowered from 8 per cent to 1 per cent, there is mandatory exemption from stamp duty and other levies, and extra floor area ratio and transferable development rights are granted to compensate for the lower profit margin in the sector.

The additional costs of thermal comfort design, material and walling assembly need to be addressed. The estimates shows that the combined impact of material choices (based on these new technologies) and architectural design solutions can push up the incremental cost by about  20-35 per cent compared to conventional construction considering the current construction costs and material penetration in states. The current fiscal strategy will have to address this.

If not addressed, the burden of the extra cost of meeting thermal comfort requirement will fall on the beneficiaries. Any stimulus for the sector should be performance-based. This will also require better assessment of affordability in different markets based on better profiling of income to housing prices, price to income ratio etc.   

Fiscal support to new materials needs to be linked with mandatory thermal comfort attributes:TheMinistry of Housing and Urban Affairs has taken an important step forward to support and fast track rental housing in response to the migrant crisis during the pandemic. The new vertical – Affordable Rental Housing Complexes (ARHC), for ease of living for urban migrants and the poor acknowledges COVID19 and reverse migration of workers, the compromised living conditions in slums and the need for ‘dignified living’. This has linked Technology Innovation Fund with the new generation materials and BMPTC is responsible for creating the compendium of materials with their attributes including thermal performance,as well as assess their adoption in housing under PMAY and rental vertical.

The additional Technology Innovation Grant for the projects using innovative and alternate technology is linked with speed of construction, sustainable resource efficient and disaster resilient construction. But the sustainable resource efficiency need to be defined to include mandatory thermal comfort within its scope to include requirements of ECBC-R for better adoption of design and orientation approaches for improved thermal comfort. Material choices need to be informed with specific indicators on orientation correction, natural ventilation, improved shading, enhanced thermal resistance, and reduced surface exposure to reduce the heat load on the structures. Performance criteria will improve operational efficiency and increase thermally comfortable hours in a year helping to reduce the need for air conditioning that has huge energy penalty.

The way ahead

Speaking at the webinar, CSE director general SunitaNarain said: “Moving towards a ‘thermal comfort for all’ approach and making a thermal comfort standard as the central focus of building regulations and practice — as the India Cooling Action Plan has asked for — will require a diverse and broad-based approach. While taking steps to frame and operationalise thermal comfort standards for buildings,we must combine design and technology to reduce the thermal load on buildings and operational hours of active cooling.”

What the CSE assessment recommends:

  • Guide the housing sector on alternative material and construction technologies
  • Promote adaptive thermal comfort standards
  • Need fiscal strategies to minimize cost of improving thermal comfort and new construction technologies. Otherwise beneficiary will end up paying the operational cost.
  • Developing thermal performance criteria for funding and link subsidies and incentives with the performance of the housing stock
  • integrate regulatory instruments like EIA, building byelaws, etc. with thermal performance criteria. Disclosure systems will be a must.
  • Shift policy focus from only constructing the housing stock to green performance and lowering of the operational cost burden for beneficiaries. Expensive new walling technologies bear a high risk of increasing beneficiary’s household energy expenditure 
  • Need improved criteria for assessing affordability establishing affordable housing price-to-income ratios in cities in the post COVID-19 scenario
  • Need instruments of accountability and a disclosure system for availing incentives.

Reference : News in PIB

Pratyusha Mukherjee
Pratyusha Mukherjee

By Ms. Pratyusha Mukherjee, a Senior Journalist working for BBC and other media outlets, also a special contributor to IBG News & IBG NEWS BANGLA. In her illustrated career she has covered many major events.