A recent study by Indian Institute of Science (IISC), Bangalore, has revealed that energy consumption by homes in Chennai contributes to 39 per cent of the city’s emissions and consequent carbon footprint.
As per the study, electricity for lighting/household appliances and fuel for cooking (liquefied petroleum gas, piped natural gas and kerosene) were the major culprits.
Apparently, poor home design and an increase in the number of glass and high rise buildings are the major reasons for excessive electricity consumption by Chennai’s domestic sector. Green building consultant Sumitra Vasudevan suggests how homes can be designed to consume less electricity.
What are the most common design and architectural flaws that lead to unwarranted electricity consumption?
Windows on two different walls of rooms to provide natural lighting and cross ventilation are important design elements. They are sorely lacking in many buildings. Another flaw is overexposure through huge windows on the western side, which increases heat gain.
Landscaped terraces at various levels, which keep buildings cool and improve quality of air, are rather conspicuously absent or very few in Chennai.
How should we orient our buildings, considering the city’s geographic location?
The right orientation with respect to the solar path and wind goes a long way in reducing heat gain. For instance, in a rectangular building, place the utilities on the western side so this area bears the brunt of the heat gain, leaving the living spaces cooler. Give ventilation openings on the southern and eastern sides (especially near the coast) as Chennai gets its breeze largely from southern and eastern directions. Orientation in terms of interiors has to be considered too. For instance, if the TV/computer monitors are oriented perpendicular to the window area, then windows can be kept open and artificial lighting can be avoided.
Is it structurally safe to rectify design flaws?
It is easier to do the changes in an independent house, like creating window openings under a structural engineer’s supervision.
Even in apartments, you can incorporate insulation for western windows by going in for a second layer of windows for the same opening, additional shading devices, waterproofing and landscaping of terraces.
What materials and design elements do you recommend for new constructions?
Use insulating materials for walls such as terracotta hollow blocks, apply terrace surface insulation before laying the terrace tiles, and waterproof the terrace so you can have a roof garden to reduce the temperature. Use insulation for exposed roofs and terrace floors with high solar reflective index materials in light colour finishes to reflect heat.
Design windows that seal spaces and do not allow leakage of conditioned air, shading devices for all windows. You could also tap into solar energy and use LED lighting fixtures.
Does using such green materials involve additional investment? If so, how long would it take to break-even?
Only some of these green elements may involve about a 5 per cent increase in cost compared to the other kinds of material, but even this pays off in the long run. Meanwhile, some green materials like terracotta hollow blocks actually come cheaper now.
Overall, constructing a green home doesn’t cost much: it only involves an awareness of green options and thoughtfulness.
