The results show the rainwater-harvesting systems are the most commonly preferred, followed by solar water-heating systems, and organic composting.

Two hundred and seventy-nine housing societies have adopted rainwater harvesting, 25 have installed solar heating systems, and 85 are cutting down on the garbage by composting solid waste.

Last week, Milan Vihar Housing Society in IP Extension also inaugurated a rainwater harvesting system.

Among the city’s residential areas, Dwarka is the most environmentally conscious: 68 housing societies practise rainwater harvesting in the planned sub-city. Many societies have also showed interest in setting up eco-friendly systems: 623 societies want to harvest rainwater and 739 want to try solar heaters.

Interestingly, many want to experiment with the little-known Organic Waste Composters, which churn kitchen waste and convert them to compost. Many housing societies have written to the government to set up these systems.

The Delhi government provides financial aid to housing societies if they want to go for solar heaters - 30 per cent of the cost, and institutions are subsidised further by the Power department. Up to 50 per cent help is given for rainwater-harvesting systems.

A government official said: “The purpose of the study was to engage with housing societies. We wanted to check good practices and the level of awareness in terms of energy efficiency or conservation of water.”

“Many societies said they were not aware of these systems or the subsidies offered. Many, for example, were interested in cutting down energy bills, but thought the solar-heating system was too expensive. They were not aware of the subsidy offered by the government,” the official added.

While Dwarka has the highest awareness levels in terms of rainwater harvesting, with most using housing society corpus funds for the purpose, they still face several teething problems — water being contaminated by soap water for instance.