It’s time to either optimize window to wall ratio or adopting efficient exterior glazing type in Buildings.

Published by firstgreen on

In recent years we have seen that many commercial buildings are coming up as a whole glass buildings. In Indian context buildings with full glass is not desirable as the larger amount of glazing leads to a huge amount of heat gain of overall building. Hence, it becomes important to optimise the building design with significant window to wall ratio.

The appropriate building w/w ratio has been practiced by various developers. However, w/w ratio typically ranging between 20-30%. In some of the buildings it ranges between 40-50%.

In a brief we can say that more the w/w ratio, higher will be the buildings overall consumption.

Although In order to explain the impact of type of glazing with respect to different w/w ratio on energy consumption of a commercial building we have analysed a building in Gurugram with 4 different types of glass with gross façade area ranging from 20-80%.

The annual energy consumption was calculated in 4 different scenarios with use of four different types with gross façade area ranging from 20-80%.

Following Glass types were used

Type 1 -Single-glazed clear

Type 2 – Double-glazed clear

Type 3 -Double-glazed low e

Type 4 -Triple-glazed low-e

The annual energy consumption is compared with four glazing types as the glazing areas is increased from 20% to 80% is shown in the graph below

From this study we conclude that the efficiency of different types of glass is in the following order

Type 4 > Type 3 > Type 2 > Type 1

Also energy simulation of a building envelope is performed by us on an energy modelling tool in 5 scenarios with same type of glazing but changing the w/w ratio at 10%, 30%, 50%, 70% & 90%.

The annual energy consumption outcomes with respect to the different w/w ratio is shown in the graph below

Thus, from above graph it is concluded that the annual energy consumption increases with the increase in the w/w ratio in huge manner.


The article dedicates considerable attention to how we can minimize the energy consumption associated with increased glazing area by using Triple-glazed low-e type of glass.

Also, the w/w ratio effects the annual energy consumption of a building envelope in significant manner.