CapitaGreen is a 82,000 sq.m., 43-floor skyscraper in the Central Business District of Singapore1. The Video looks at its design for Sustainable Ventilation.
45 m1 tall Wind-Catchers atop the skyscraper are oriented towards the prevailing wind direction2. Designed to scoop winds at this elevation, they channel air down a core known as the ‘Cool Void’3. Air from the cool void spreads horizontally through the levels, reducing Air-Conditioning loads.
While researching various Passive Strategies and Technologies for the Building Envelope, we came across ‘Cool Roofs‘. We realized that this is a simple, low cost technology with large potential benefits. These include – Energy savings, Reduction of Urban Heat Island Effect and Greenhouse Gas Emissions, enhanced Durability of roofs, and Resilience to extreme heat 1.
Thus, this week’s Article and Video are dedicated to this important idea. The Video 2 , 3 , 4 outlines the Need for Cool Roofs and how they Protect Buildings. In the Article, we cover Initiatives by various parties working in the direction. We also look at some successful Case-Studies that could become models for future developments.
Due to multiple possible benefits, the technology has caught the attention of International actors, Indian central, state and local governments, as well as the Private sector. Their attempt is to use Cool Roofs for large scale Impact at the Building and Urban scales.
The Bureau of Energy Efficiency [(BEE), Government of India, Ministry of Power], has prepared a ‘Cool Roof Design Manual‘ 2 to spread technical information about Cool Roofs for the Composite Climate Zone of India.
A Fact Sheet5 and Issue brief6 have been released by Natural Resources Defense Council (NRDC) and Partners to showcase local projects, and to spread the message, so that action can be scaled up.
Green Building Rating systems like LEED, GRIHA, IGBC need compliance with the Energy Conservation Building Code (ECBC) norms. ECBC specifies minimum cool roof values (reflectance and emittance), for roofs with different slopes 6.
IIIT Hyderabad Cool Roof Calculator – The simulation tool by IIIT Hyderabad, uses a base and design case for testing various roof conditions in certain cities of India. A percentage change in cooling energy can be compared 2, 7.
The above efforts are helping common people as well as experts to understand and utilize Cool Roofs, by providing technical information, tools and answers to common questions. The following examples showcase successes in the field.
Ahmedabad’s Cool Roof Initiative, as part of its ‘Heat Action Plan‘ aims to convert 3000 roofs in 6 zones to Cool Roofs. This is being undertaken by city staff and student volunteers. They are using white lime paint, which costs as little as ₹0.50 per square foot 5.
Hyderabad is also witnessing a Cool Roof Initiative as part of its Building Energy Efficiency Program. The Pilot included 25 city roofs in low income areas. A High-Density Polyethylene (HDPE) cool roof membrane (costing ₹13 per square foot in Hyderabad) was supplied by Dupont as part of their CSR initiative 1.
The Indore and Surat ‘Cool Roof Project‘ is using local success stories to make a case for cool roof policies in the future. The project consists of over 100 households. They are using simple materials such as lime concrete, broken earthen pots, China mosaic tiles 6.
A Joint study was conducted by International Institute of Information Technology, Hyderabad (IIIT) and Lawrence Berkeley National Laboratory (LBNL) on 2 office buildings in Hyderabad. The studies saw a drop of approximately 20°C in Roof surface temperatures after application of cool roof coating 2.
We leave you with the following questions –
Have you used ‘Cool Roofs’ in your Project? Do you know of any projects using ‘Cool Roofs’?
What Benefits have you felt after application of the ‘Cool Roof’ technology?
What Problems did you face?
What kind of Assistance if any, did you receive from the Government or any other organisations?
Let us know! We would love to provide a platform, to showcase your project and spread more useful information.
Jaiswal A, Bhagavatula L, Awasthi A, Sarkar S. Keeping It Cool: Models for City Cool Roof Programs. National Resources Defense Council. https://on.nrdc.org/2jLgLPJ. Published 2018. Accessed November 27, 2018.
International Institute of Information Technology Hyderabad, Administrative Staff College of India, Indian Institute of Public Health Gandhinagar, Mahila Housing SEWA Trust. Keeping It Cool: How Cool Roofs Programs Protect People, Save Energy and Fight Climate Change.; 2018. https://on.nrdc.org/2FIxYas. Accessed November 27, 2018.
International Institute of Information Technology Hyderabad, Administrative Staff College of India, Indian Institute of Public Health Gandhinagar, Mahila Housing SEWA Trust. Issue Brief – Cool Roofs: Protecting Local Communities and Saving Energy.; 2018. http://www.phfi.org. Accessed November 27, 2018.
“The harmony of natural law reveals an intelligence of such superiority that, compared with it, all the systematic thinking and acting of human beings is an utterly insignificant reflection.”
Contemplating this powerful quote by Einstein could send chills down your spine. Our insignificance in the face of Nature’s power, begs us to show more humility. Nature doesn’t fear our walls, and everyday Climate related calamities should teach us better. It is ultimately in all of our favor, to Build with Nature, instead of withstanding it!
Following this chain of thought, today we look at Integration of Built with Water. Such a synergy with Water has positive effects on Micro-Climate and Energy Loads.
However, insects can be attracted to areas of vegetation and water. While all insects are not harmful they may not always be welcome in an urban setting.
Let’s look at some ways to address this issue-
1) Deeper water could prevent mosquitoes, since larvae prefer shallow water bodies of less than 2 feet
2) Natural pest Predators like Dragonflies are garden heroes
3) Select Plant Species that repel pests – Lavender, Citronella Grass, Marigolds
Building functions can be zoned according to ventilation strategy for effective management and energy conservation. This is seen in Akshay Urja Bhavan, New Delhi where spaces are divided into zones according to setpoints– Apex, Controlled and Passive. Only around 12% of the area is air-conditioned. Mist cooling systems are used for the Controlled and Passive zones1.
A 16 km (once the campus is completed) tunnel network of Air Earth tunnels, will be running 4 m below the ground in NIIT University, Neemrana Campus. Surface temperature and seasonal variations do not penetrate below this depth, keeping air temperature constant throughout the year. Fans will pull cool air through these tunnels. This would then be taken through precipitators to eliminate dust and would be supplied to the building through ducts. The result! – Pleasant 25oC temperatures indoors, without the use of air-conditioning, when temperatures outside are nearing 50oC1.
This is Segment 4 of our Chain of posts focused on ‘Energy @ the Building Scale’.
[Extension of Part 4/5: The Red System (Energy), Singapore – Published: 28th May 2018]
Skyville@Dawson is a 111,106 sq.m., 48-storey1 public housing project by WOHA Architects in Queenstown, Singapore. It is one of two Build-To-Order (BTO) projects commissioned by Singapore’s Housing Development Board (HDB), as part of their “Remaking Our Heartland” initiative (the other being SkyTerrace@Dawson by SCDA Architects)4. This “housing-in-a-park” concept would show transferability in future projects and towns like – Waterway Terraces, Bidadari, Punggol Northshore, Tampines North6. It is the first housing development to be awarded the GreenMark Platinum Rating10. Skyville@Dawson’s Sustainable Design features including Passive Strategies are elaborated below-
(i) The Building is placed with its longer facades facing the North-South9 directions. This reduces exposure to the East and West directions, that are normally difficult to shade.
Clustering and Modules
(i) 8 apartments in plan(as seen in Plan diagrams above), surround a courtyard. This cluster is repeated 2 more times, to create 3 sets of apartments enclosing courtyards. This configuration also provides self-shading, especially from low angle rays from the East and West directions (as seen in the Shadow Studies above).
(ii) In Elevation, 12 clusters form villages, each comprising of 80 apartments.
(iii) The apartment layouts are column and beam free4. This provides the possibility of 3 layouts for residents – reducing wastage, allowing flexibility for multiple functions, family size and the future.
(iv) For standardization, efficiency and to reduce wastage, only 5 window types2 have been used in the entire development.
(v) The design uses precast and prefabricated10 elements to avoid errors and reduce wastage. This feature could also contribute towards LEED BD+C v4 Credit – Construction and Demolition waste management.
(i) The individual apartments are approximately 11 meters across in width, thus applying the Unit Thick Principle. Apartments also have openings in all directions. They are thus naturally ventilated and day lit, reducing artificial cooling and lighting costs.
Breathability – Horizontal Air Movement
(i) The clustering arrangement around courtyards, and the repetition of this module linearly, enables horizontal air circulation.
(ii) Common areas (Lobbies, Corridors, Staircases) and Apartments are naturally ventilated. Many units have not installed Air-conditioning3.
Breathability – Vertical Air Movement
(i) With minimal obstructions and the creation of Canyon like spaces, air moves vertically through the towers – accentuating the breezy atmosphere. The interaction of this air with greenery from sky gardens at intermediate levels, cools this air through evapotranspiration.
(i) ‘Sky Terraces’7 are located every 12 floors. These are designed as community spaces, where people can collect to interact with neighbors or simply visit to relax and enjoy the lush greenery.
(ii) A ‘Sky Park’7 on the roof has planters, hedges, and beautiful city views. Photovoltaics3 power the common area lighting.
Site Integration with Green and Blue
(i) A 150 m long bio-swale (gently sloping ditch with specific plants) filters and treats site stormwater before discharging it into the city drainage system5. Another example of a bio-swale – water treatment and recycling loop can be seen in Kampung Admirality.
(ii) The site is an ungated3 community, with Public Parks and Amenities that cater to the residents as well as the general public.
(i) Monsoon windows8 on the facade can be kept open during rains, thus providing cool breeze without wind-blown rain entering the home. A similar more advanced Monsoon Window design is utilized in another high-rise residential building – 1 Moulmein Rise, Singapore.
(ii) The walls on the facade have horizontal and vertical sunbreakers5. Balconies or horizontal ledges9 are used to provide shading for openings.
(iii) Double-height verandas10 on the ground level provide pleasant public spaces overlooking the parks.
That’s all for today! We hope you enjoyed this segment. As always, we would love to hear your thoughts, suggestions, queries, opinions.
See you next week.
Credits: Graphics : Selected graphics are produced as part of a team project for M.Sc. Integrated Sustainable Design at National University of Singapore (Building Semester – Stage 1 – Complex Living Systems). Group Members – Gajender Kumar Sharma, Aditi Bisen, Huang Hongbo, Zhao Yanming Text: Aditi Bisen
These faces of the building are difficult to shade, as they receive low angle rays from the rising and setting sun. Common shading features such as horizontal projections, usually fail in such situations. Our 3 case-studies explain methods to address these tricky areas of the building.
Park Royal – The East, West facades are shaded using self-shading, achieved due to the E-shape projections from the Plan.
CapitaGreen – Of all the vertical green on the facade, larger amount of greenery is provided on the East, West facades to shade them.
Cleantech One – Sky gardens and planters on these facades help cool the labs and create pleasant breakout spaces.
Credits: Graphics : All graphics are produced as part of a team project for M.Sc. Integrated Sustainable Design at National University of Singapore (Building Semester – Stage 1 – Complex Living Systems). Group Members – Gajender Kumar Sharma, Aditi Bisen, Huang Hongbo, Zhao Yanming Text: Aditi Bisen
CapitaGreen is a 82,000 sq.m. GreenMark Platinum building. It is a 43-floor skyscraper in the Central Business District of Singapore designed by Architect – Toyo Ito (2). It is at less than 10-minutes walk, South-East from Park Royal, Pickering – our previous project under study. The Skyscraper has multiple sustainable features as elaborated below; which lead to energy savings of around 4.5 GWh /year (1).
Park Royal at Pickering is a 7500 sq.m. Hotel in the thick of Singapore’s Central Business District, facing a now famous Hong Lim Park. The hotel has various sustainable features (elaborated below), that lead to approximately 30 per cent (f) energy savings in operation (using a conventional building of similar scale and functions as base case). Due to these features, it has received the GreenMark Platinum rating certification from Singapore’s Building Construction Authority.
Horizontal air movement –
Despite being a commercial project, the property shows generosity, by providing a large public interface on the ground floor. This enables Horizontal air flow, thus improving thermal comfort for the area.
The corridors, lobbies and common wash rooms are all naturally ventilated with fresh air (c).
The entrance to the above-ground car park is concealed with plants and is also naturally ventilated.
This natural ventilation in humid Singapore conditions, provides relief to occupants. The breeze, coupled with shading measures, can improve thermal comfort conditions; thus reducing the need for artificial mechanical cooling.