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