The construction sector accounts for the highest share (17%) of CO2 emissions by final demand in the Indian economy because it uses highly energy-intensive materials and the need for shelters is very high. This sector is highly vulnerable to changes in pricing structure. Various construction techniques have been analysed and it is shown that a room of length 3.5 m, breadth 3.5 m and height 3.14 m would lead to about 6 tonnes of CO2 emissions if constructed at the minimum possible cost. These costs are distributed as follows: foundation--25%, walls--46%, roof--16%, floor--4.8%, and plastering--8.6%. If cement is replaced by lime, the cost of construction increases by 0.14% for a 3% reduction in emissions. Further reduction in emissions is achieved by using stone instead of bricks. The cost increases by 0.54% for a 4% reduction. However, for a 21% reduction, the cost escalates by 27%. We also examine impacts on employment, materials used etc., due to changes in techniques.