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Case Study III: TZED homes in Bangalore by BCIL


water heating

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Lien :

Tzed@Bcil





A project developed by BCIL as a residential project consisting of environmentally sustainable and aesthetic homes for 95 families. A benchmark in SBE development in India.

TZED (ZED stands for Zero Energy Development) is located at airport Whitefield Road, Bangalore. This five-acre site comprises of 95 homes built on the principles of sustainable resources.

The great value of this experience lies in the demonstration, that modern comfort standards can still be met while associating with the principles of sustainable built environment, under the purview of the challenges posed by real estate market mechanisms and cost constraints.

The objective of BCIL was to build a campus for a self-reliant community, with autonomy in Water and Energy related issues and processes for Solid Waste and Wastewater management.

Every aspect of T Zed has been designed to conserve natural resources and to have minimal impact on the environment. In these homes, built-in, customized environment-friendly, zero electricity refrigerators, fully controlled air conditioning based 100 % on fresh air inputs, and built-in energy efficient lights are among the features that help to bring down energy consumption in the home while ensuring comfort levels and commanding a higher market value.

Approach

TZED is so called because it aims at drastically reducing the carbon emissions in the whole life cycle of the building (construction, actual life and destruction) without compromising on the high-energy life style of the inhabitants. TZED is thus the first residential project in India to have sought Carbon credits or Certified Emission Reduction (CERs) under the Clean Development Mechanism initiatives.

The project has been worked out towards achieving this collective goal, by addressing the following six main areas - design, building material, water, waste, quality of air and energy management through innovative interventions.

Design:

The total number of homes is based on the carrying capacity of the land: to ensure the autonomy in water the amount of water harvested from the annual rainfall is calculated and gives the feeding capacity of the land which is divided by the annual average consumption of a modern family, giving at last the maximum figures for settlement.

The master plan consists in two parallel four-floor buildings containing a street for pedestrian and vehicles movements along it. The south-facing buildings are segmented into blocks in order to provide maximum natural light to the street and homes located in the second row of buildings. These cavities called “e-zone” are treated as garden for recreation.

Materials:

TZed uses building technologies and materials (like stone and mud) that reduces carbon emission through savings on resources and embodied energies.

BCIL has used filler slabs, incorporating fly ash blocks, to save the amount of steel and cement used.

External walls are built using soil-stabilised blocks (around five lakhs have been used), laterite blocks and finishing treated with fine waterproof coating. This ensures that surfaces are non-erodable, need no external paint applications and are thermally efficient.

Green roofs or “sky gardens” also contribute to the thermal comfort of the dwellings. These provide a planting space for every home while serving as thermal insulation for adjoining and lower built spaces. Each sky garden uses lightweight mulch and coir pith instead of heavier soil, and is irrigated via a drip method.

Rubberwood, a non-forest timber, is used for door shutters and as flooring. Palm wood has been used for external walkway decking. They have also used compressed coir door panels for the door shutters, while bamboo composites provide roofing for part of the club and the interior woodwork in places. These are local resources that use less energy to produce, thus reducing carbon emissions.

Water:

A self sufficient and secure water supply system is also provided, using the rainwater collected from the roofs, which is stored in shallow aquifers, through a system of drains, percolation pits, trenches and wells. Around 44 recharge wells are dug to help water percolation through the ground into the shallow zone. Four bore wells act as backup for water in extreme conditions of shortage of harvested water, these wells are equipped with sand filters and ozonation systems.
Solar water pumps draw this water from the shallow aquifers into a transit tanks from where it is sent for ozonizing thereby making it potable. Then it is sent to small overhead tanks for daily storage before it reaches the homes. Hot water is always available as solar water heaters have been installed.

There is no sewerage connection for this campus. All wastewater (grey water) is treated, through a process of filtration, aeration and ozonization to be reused for gardens in a way that such water eventually percolates into the open wells and so completing the loop of use and generation. This treated water also finds it way into the water closets of the individual homes.

Energy:

Centralised district refrigeration system and air conditioning system using an ammonia-based chilling unit (non ozone depleting product) has been provided to the campus. Such strategy allows large economy of scale and also means that there are no compressors in the individual refrigeration units installed in each home. This in turn enables better management of cooling needs and more space for storage within each fridge.
Intelligent lighting systems blend motion sensors, ambient light sensors and timers to ensure that lights are switched off when not needed. Compact fluorescent lamps and light emitting diodes (LED’s) are used for common areas, cutting power consumption by up to 80 per cent while protecting lighting efficiency.
Each home also has “conscience meters”, monitoring electric watts and water consumption. An electrical watt- meter fitted in each home indicates the wattage used at a particular time and thus allows users to monitor their power consumption and introduce efficiencies. Meters on the kitchen and bathroom taps help to monitor the volume of water used in litres.

Waste:

Kitchen wastes are segregated into organic /inorganic wastes. Organic waste goes to the vermicomposting pits where they are converted into Vermicompost, a nutrient-rich natural fertilizer and soil conditioner to be used for the garden.
Black water from the toilets and bathroom proceed toward the Sewage Treatment Plant, an anaerobic digester where 70% of the biological matter is decomposed. Grey water proceeds to a decentralised water treatment system, which then passes through an root zone treatment system. This water is used for irrigation of herbs, plants and grass and finally joins the shallow aquifer.

Air:

TZed’s ACs bring 100% fresh-air compared to the regular AC, which gets only 80% fresh air in over 24 hours of working.

Some achievements:

•TZed is a campus that has no water supply connection from the outside.

•There is no sewerage connection for this campus. All wastewater is treated and reused for gardens in a way that such water eventually percolates into the open wells and so completes the loop of use and generation.

•This is India’s first centrally air-conditioned (with no CFC and HCFC) residential campus.

•The Capital savings of approx 20,000 tonnes of Carbon emissions.

•The Revenue savings of approx 1500 tonnes of Carbon emissions.

•Tzed consumes only 60 per cent of energy demand of a 100 houses anywhere else. Residents pay 30 % less on power and 20 % less on monthly maintenance.

•Every resident gains Rs. 12,000/- on an annual basis, thanks to carbon credit savings in T-Zed.

Conclusion

Through the project, BCIL has made an effort to provide modern comfortable housing and at the same time, minimize the environmental impact. The various technologies and design techniques used in the construction are all well known and have been successfully implemented in the past. The advantage lies in incorporating many technologies together in a single project, which is exactly what BCIL has achieved through T-ZED homes. BCIL has stated its long-term commitment to quality housing and strong sustainable communities as one of the reasons behind the T-ZED homes project. It serves as a model for energy conscious development in urban locations.

This experience has given rise to many difficulties -successfully worked out. But despite difficulties faced, one has to appreciate the risks taken by this organisation for having addressed sustainable issues at a larger scale while confining themselves within the frame of the market rules.


Location: Airport Whitefield Road, Bangalore

Area: 5 Acres

80 apartments, 15 independent homes

Super Built-up Area: 2155 Sft. to 3537 Sft.