Fact File
Project size: 876sqm (9429.19 sqft)Location: Chennai
Completion status: Civil in progress (90% completed)
Sustainable features have been considered in all aspects of this modern zero carbon residence built on a 1645 sq.m site in the Santhome area of Chennai, with a built up area of 875.6 sq.m. Photovoltaic panels, smart water management systems and other energy-efficient features have been integrated into the frame of the house without the need for additional wings. On the inside is a space-conscious single wall kitchen, a loft bedroom, and a tiny living area. The house has over 60% energy efficiency, passive cooling techniques and automated technology to control everything from the home gadgets and security to Wi-Fi.
The initial massing of the structure was done keeping in mind the following: The site planning was performed taking into consideration Vaastu Shastra and local code requirements, which specify the front setback as 3m and side and rear setbacks as 1.5m, with a floor space index of 2. The maximum height of the structure (after taking into consideration the abutting road widths) was 12m (3 storeys). The form development began with exploring aerodynamic forms, hence, environmental simulations were run for the parameters of ventilation and solar radiation to study the effect these natural factors have on the structure. The massing was further optimized based on the findings of these simulations to enhance natural ventilation and reduce the heat gain of the structure due to solar radiation. The addition of a courtyard cutout allows only indirect sunlight to enter the spaces. An attempt to reduce the solar heat gain was made by scaling the walls and incorporating a change in the roof levels. The continuous form along with the internal planning allowed for unhindered movement of wind through it. The window-to-wall ratio is maintained at 21%.
The residence has two courtyards that provide sufficient daylight indoors. Windows on all four facades bring in maximum sunlight without causing glare. The windows are designed such that an average 89% of the building has illuminance greater than 100 lux on a typical day. Building has glass of VLT 50%, U-Value of 1.5 W/m2C and SHGC of 0.28. The building was also designed to have wall, floor, and ceiling reflectance as 60%, 20% and 80%, respectively. All the given units achieve adequate daylighting levels between 150 - 5000 lux with a floor plate distribution of greater than 83% for all typologies, thus complying with LEED requirements.
Environmentally preferrable alternatives were considered as much as possible for each building element. PPC cement which has fly ash content was used for plain cement concrete in the foundation. The building’s super structure was made of self-compacting ready-mix concrete M35 grade with 350 + 100 (kg/cu.m) GBBS/Fly Ash content. The partition walls are made of Aerocon blocks having 30% recycled content, and the wood used is FSC certified.
The home of the future needs to be one that does not depend on grid for power and resources. Its design should aim to protect the environment and the natural resources, recreate urban areas and buildings that are designed to fully cover their energy requirements without inducing environmental damage.
Suraksha Acharya
On the façade, the glass used is of Saint Gobain having 30% recycled content. The water required for the project is sourced from municipal supply as well as rainwater harvesting. The total water requirement of the project is 2000 LPD for domestic use and 1000 LPD for flushing. Considering an average rainfall of 0.025 mm/day, around 8000 LPD of rainwater can be harvested from roof and non-roof structures. Rainwater harvesting sump of capacity 12000 liters is provided on site and the rest is used for ground water recharge using percolation pits. Thus, 100% of rainwater is harvested from the site for planning for future water scarcity in the city.
An STP of capacity 2000 LPD is installed at site to treat the wastewater. After treatment, around 900 LPD is available for reuse for landscape irrigation. The treated greywater has a PH Value of 6-8, which is suitable for landscaping. This quantity meets 65% of the irrigation needs of the vegetation provided on site. To further reduce the water consumed by the project, water efficient plumbing fixtures with flowrates lower than the industry average are used. Use of low flow water closets, faucets, and showerheads result in a 73% reduction in water consumption compared to the baseline. Fixtures like basin mixers and air injected shower heads save up to 70% water consumption by using flow regulators in comparison to conventional water fixtures. Water metering is done for the project to monitor water consumption.
Meeting energy performance targets of the project is achieved by improving envelope performance, lighting, HVAC, and hot water equipment. Efficient double glazing, RCC walls with shading elements, solar panels on the roof, efficient lighting fixtures that consume less power, are employed along with occupancy sensors. The lighting load incurred is around 5000 kWh/Yr.
The proposed TOSHIBA HVAC system consists of primarily VRF system serving the bedrooms, living rooms, and dining areas, and one 14 HP and two 10HP VRF Systems, serving each floor individually, one 6 HP VRF Treated Fresh Air unit using R-410A refrigerant of 3.5, 4.26, 4.81. The HVAC system was supplied by Carrier Air Conditioning & Refrigeration, as advised by HVAC Enersave Solutions and executed by Enmac system. The cooling load incurred by the structure is around 15,000 kWh/Yr. The structure is ventilated with exhaust fans of 800 CFM fans. Hot water requirements of the household are met using a solar water heater.
The energy efficiency measures resulted in energy and cost savings of 5.7% compared to a baseline building developed in accordance with ASHRAE. Along with reducing the total energy consumption, the residence is designed to be self-reliant for its energy needs. The Solar PV system is proposed to have 66 panels with 370kWp panel capacity. The percentage of energy generated by renewable energy system as compared to the energy required by the structure is 131.5%.
The addition of renewable energy generated by the project resulted in an excess of 1,460 kWh per year that is supplied to the grid. Thus, the residence became a Net Zero Energy Building by producing more energy than it consumes. The EPI of the project is 45.83 kWh/sq.m year. These measures enhanced the energy performance of the structure and helped it achieve Net Zero. The planning and execution of this design was carried out by Midori Architects.
At the construction site, dust suppression measures were carried out to protect the health and safety of workers as well as prevent air pollution. Watering of sand and aggregates, single point entry, site barricading and covering of site construction materials were employed. Soil erosion in the site was controlled by preserving the topsoil, construction of rainwater ditches and swales and proper staging. Vegetation on site was preserved through barricading of trees.
With an aim to reduce absorption of heat by the building mass and thus reduce the heat island effect, many shading elements are incorporated into the design. The external walls are inclined at an angle of 80 deg. to incorporate self-shading into the structure. After the shading elements were introduced, the amount of solar Insolation reduced significantly by 71%, which in turn directly reduced the effect on the heat gained indoors. The perforated grass pavers, vertical and horizontal landscape, also helps to mitigate the heat island effect of the building.
One charging point is provided for electric cars, reducing the negative impact of fossil fuel-based automobile use. Household waste of the residence is segregated at source, using a 3-bin collection system: yellow for recyclable items, green bin containing organic items, and red for containing non-recyclable items. 100% of the organic waste is treated onsite by a waste treatment system, which processes all organic kitchen waste and converts it into compost which can be collected every two weeks. This reduces waste at source and recycles it into compost which can be reused as compost for gardening and farming.
Major retrofitting solutions includes using renewable energy to contribute positively to the grid, low SHGC window to prevent radiation through glass, cavity tiles and double roof canopy, to prevent direct solar radiation through home automation controls like motion sensor & occupancy sensor to reduce the lighting load, with the above investments resulting in a payback period of 6.5 yrs. Overall cost, is Rs. 700 per sq. ft more than that of a conventional building.
This energy efficient homes boasts of impeccable green credentials, stylish sustainable and efficient living, this eco-friendly home aims to inspire others to take a similar approach to future home design. These measures along with the collaboration of various members of the project team helped achieve the LEED Platinum rating for Multifamily residences.
