Cantilever House

Online Exclusive Feature, Residential / 2021

Cantilever House

March 17, 2021

The Cantilever House takes into account the harsh North Indian climate by employing a series of mechanisms. They minimise resource consumption and reduce the building’s environmental impact while enhancing the residents’ thermal comfort.

ORIENTATION & SHADING

The house records minimal heat gain throughout the day by placing the living areas in the north and the east to bring in sufficient daylight, and by allocating space for private rooms in the west and the south.

The residence’s double-height lobby is flanked by a summer court on the north and a winter court on the south to enable stack ventilation at all times. The night-time spaces are characterised by optimum thermal mass to protect the day-time spaces from the south and west sun.

The north face of the house is glazed to admit diffused daylight and avoid heat gain and glare. The design minimised the number of windows on the south façade to prevent heat gain; these were further shaded with the addition of a pergola. The façade is fitted with double-glazed units with low-E coating for thermal resistance. Nearly all glazing for the day-time spaces is designed to open into the water court.

By bringing in elements of nature to the interior spaces, the house establishes a strong visual connection with the outdoor landscape. The integration of landscape features with the built envelope ensures a cool microclimate for the residents.

The water court on the north serves as a heat sink. The plants and vertical garden also contribute to thermal comfort while purifying the air by trapping dust and pollutants. The front and rear lawns, along with the water court, serve as recharge pits for rainwater harvesting. The residents’ hot water requirements are met by evacuated tube solar hot water systems installed on the rooftop.

RESOURCES

The interiors comprise a material palette that features varying hues of browns and greys that are derived from the use of wood and concrete. All the materials were sourced locally, available within a radius of 200 kilometres. The house offers cosy nooks, designed for comfort and well-being.

The brick wall has been used extensively as a thermal mass in addition to the reinforced concrete slabs. For the fenestration, double-insulated glass with a U-value of 1.8 was used to minimise solar heat gain. The powder-coated external jaali/screens and pergola on the north and the south helped in reducing the direct heat gain on the principal façade. Further, lightweight blocks were used as an infill material for the cantilevered block at the front, thus optimising the steel requirement.

Low volatile organic compounds (VOC) paints in pastel colour tones have been used on the walls to prioritise health concerns. Additionally, LED lights were installed to reduce the overall electrical load. The residence is also home to a curated selection of indoor plants that help improve the indoor air quality through the day.

PERFORMANCE

By increasing the floor heights, bringing in ample natural ventilation and creating a link between the principal spaces and the transition spaces, the required cooling load of the building was lowered by 32 per cent (%), which is more than the Energy Conservation Building Code (ECBC) base case.

The house has been heavily insulated through its form and physical considerations, through both passive and active design strategies. The chosen material palette, deep overhangs and water courts help bring down the Energy Performance Index (EPI) by 35% below the ECBC base case.

Additionally, the selection of materials and construction activities were carried out in line with SVAGRIHA (Simple Versatile Affordable GRIHA). This can be seen from retaining the topsoil for gardening, managing the generated waste to contractor and labour management. This was done to minimise the airborne pollution through the duration of the construction.

The residence was designed such that the night-time areas overlap the day-time areas in the south and north directions. This was guided by passive cooling and daylighting considerations. All the day-time areas have been designed with greater ceiling heights and attached to transition spaces. The walls have been oriented and shaded by cantilevers to prevent heat gain from the direct and diffused solar radiations through the day. Further, natural ventilation was achieved via the interior water court that allowed for cooler and cleaner air through evaporative cooling.

SOCIAL AGENDA

The Cantilever House is located in Raj Nagar, Ghaziabad, between an industrial belt and a large residential neighbourhood. For the construction of the project, workers form the local neighbourhoods were involved in the construction of the residence.

To construct the large steel cantilevers judiciously, to ensure economic viability, and incorporate adequate steel reinforcement for structural integrity, the workers from the local community had to be trained to achieve the required skill of construction. Hence, the project not only provided a source of livelihood to the workers but also was a means of skill development and training in construction.

CHALLENGES

Since the cantilever formed a dominant part of the design, and a typical cantilever demands the use of steel to generate structural integrity, the primary challenge was to devise the frame with minimal use of steel to make the design economically viable. This has been achieved through the calculation and incorporation of the required steel reinforcement needed to provide structural stability to the cantilever. Additionally, the client was initially unsure about the design, and the workers on-site had to be trained to execute the cantilever’s construction.

Another challenge was generating a cohesive design vocabulary that allowed for privacy while still creating a connected space to satisfy a typical family’s needs. In response to this, the design took shape through the distribution of various private areas and varying volumes that were planned to account for the diversity of usage based on the time of the day and privacy required. A series of connected living spaces, courtyards and bedrooms were linked with the intent of creating a home that could be brought to life throughout the day.

PROJECT DATA

Project NameCantilever House
LocationRaj Nagar, Ghaziabad, Uttar Pradesh, India
Completion Date (If project is completed)April 2020
Site Area830 square metres
Gross Floor Area725 square metres
Number of Rooms5
Building Height12 metres
Client/OwnerKaranveer Singh
Architecture FirmZED Lab, New Delhi
Principal ArchitectsSachin Rastogi; Payal Seth Rastogi
Main ContractorDesign Solutions
Mechanical & Electrical EngineerDesign Solutions
Civil & Structural EngineerDesign Solutions
Images/PhotosStudio Noughts and Crosses; Andre J. Fanthome

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