MAKING SENSE OF WEATHER

Most vernacular architecture is highly climate responsive. Our forefathers had a very good observational understanding of the climate and their architecture exploited the maximum benefits of the climate while keeping out all unwanted elements effectively. However, now with dense cities, quick construction practices, limitation of resources, it is difficult to think like our ancestors and build climate responsive architecture. With an effort to improve the quality of the built environment, the concept of green buildings is making an appearance.

A good understanding of the weather is key to any Green Building design. Weather data is available freely and abundantly for most of the geographical locations. Understanding and learning the weather patterns and climatic conditions can be a daunting task and applying it into design can be even more troublesome. Here is a simple guide on referring to climate data, interpreting them and what it means. Lets do it with the help of weather data for Chennai, India

weather

Daylight Hours: This indicates the number of hours of available daylight in a month. Since, Chennai is located quite close to the equator, the daylight hours does not vary too much throughout the year. Northern Latitudes may however experience variation in the daylight from the summer to winter months. This data should help you in understanding that sometimes in winter you may not have sufficient daylight and the artificial lighting should emulate Daylighting wherever possible.

Radiation: Indicated in W/m2, this data tells you the amount of direct heat received from the sun and the sky. Your simulation software will use this data to calculate the heat gains on various surfaces.

Temperature: Temperature is the most easily recognisable weather parameter. This, coupled with relative humidity, gives a very close indication of the thermal comfort levels and also cooling and heating requirements. Chennai’s temperature ranges from around 18 Deg C to 40 Deg C and requires cooling strategies for most of the year.

Relative Humidity: Relative Humidity is another key thermal comfort factor. Higher humidity means your sweat will not evaporate quickly and you will end up feeling sticky and uncomfortable. Chennai experiences high humidity of about 75% due to its coastal location. This means ventilation is a very key requirement in ensuring thermal comfort. On the other hand low humidity can leave you feeling dry and itchy

Rainfall:Based on where you are, the rainfall patterns are likely to vary. The monsoon in India follows a predictable pattern to a certain extent. Chennai experiences rainfall from the North-East monsoon predominantly during October and November. The rainfall data must be used to plan rainwater harvesting structures and storage devices.

Wind: The diagram known as the wind rose indicates the direction and intensity of wind speeds. The Longer the Spike in the wind rose, the higher the wind speed.

Simulation software today is capable of simulating 8760 hours of weather data to give a complete understanding of how the weather works through the year. However, architects and other designers should understand in principle the weather of a region to ingrain their effects into a design from the beginning.

Weather Data sourced from energy plus weather data.

http://apps1.eere.energy.gov/buildings/energyplus/cfm/weather_data3.cfm/region=2_asia_wmo_region_2/country=IND/cname=India

Weather File Image from the weather tool