Building Orientation Effect in Mumbai – A Short Study

Mumbai is warm and humid. There has been always a necessity to design a building which will be energy efficient due to its physical location, building orientation and layout. The example we describe here may not be practical but will definitely give an indication on how to orient a building to get maximum advantage. Maximum Dry Bulb Temperature of Mumbai is 35.8 Deg C. The design weather data is shown below:-

Report: Climatic Data Summary

For: Entire Facility

Timestamp: 2017-02-06 22:04:13

SizingPeriod:DesignDay

Maximum Dry Bulb [C] Daily Temperature Range [deltaC] Humidity Value Humidity Type Wind Speed [m/s] Wind Direction
MUMBAI ANN CLG .4% CONDNS DB=>MWB 35.80 5.60 23.00 Wetbulb [C] 3.30 320.00
MUMBAI ANN CLG .4% CONDNS DP=>MDB 29.90 5.60 26.80 Dewpoint [C] 3.30 320.00
MUMBAI ANN CLG .4% CONDNS ENTH=>MDB 31.70 5.60 88800.00 Enthalpy [J/kg] 3.30 320.00
MUMBAI ANN CLG .4% CONDNS WB=>MDB 31.40 5.60 27.70 Wetbulb [C] 3.30 320.00
MUMBAI ANN HTG 99.6% CONDNS DB 16.50 0.00 16.50 Wetbulb [C] 0.30 90.00
MUMBAI ANN HTG WIND 99.6% CONDNS WS=>MCDB 26.20 0.00 26.20 Wetbulb [C] 6.10 90.00
MUMBAI ANN HUM_N 99.6% CONDNS DP=>MCDB 25.90 0.00 6.00 Dewpoint [C] 0.30 90.00

The above details give a fair bit of idea about Mumbai’s weather details.  Now let’s consider that we have a 3 by 3.7 m Bedroom where the Internal Walls  are assumed as Adiabatic and they have been shown in Pink and External walls are shown in Grey.  There is a window on southern and western face. The external walls have 230 mm and Internal Walls have 115 mm Brick Work. The Glazing in Window is 6 mm Thk. The roof and floor are 200 mm Thk RCC.

The Bedroom is used from 2100 Hrs to 700 Hrs on weekdays and 1400 Hrs to 1700 Hrs & again from 2100 Hrs to 700 Hrs on weekends. The Bedroom has a Unitary AC which is generally used for cooling. There are fans and LEDs in the room. The LEDs have been used in the room for internal lighting purpose.

We have used four envelope rotation variation in the direction to study the effect of building orientation on the energy consumption. The baseline model has been considered as the one which has been shown here.  The most energy efficient model by way of energy consumption works out to be the one which is turned in clock wise direction by 90 deg. The major energy consumption has been in the cooling of the area. There is no requirement of the Heating as Mumbai weather condition doesn’t require that.

This model saves energy by about 14%. This is proved logically also as in the rotated model the both the windows are away from the sun’s glare and heating of the internal portion is minimum.

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