The Month of the Equinox

Last month, September, was the month of the equinox. A year sees four watershed touch points of seasons – the two equinoxes and the two solstices.
Equinox is when the day and night are approximately equal across the earth. It also means that the sun rises and sets exactly in east and west respectively. Equinoxes happen between March 20th to 23rd and September 20th to 23rd annually. The actual date may vary from year to year.
The solstices are when days and nights are the longest or the shortest depending on the hemisphere one is in. December 21st to 23rd sees the shortest day and longest day in the northern hemisphere and vice versa in the southern hemisphere. June 21st to 23rd sees the longest day and shortest night in the northern hemisphere and vice versa in the southern hemisphere.

Everything is about the angle

Its fascinating that something like this happens – all because of the tilt in the axis around which the earth rotates. The earth’s tilt is around 23.5 degrees from the vertical. When the earth revolves around the sun, it’s only natural that the parts of the earth receive sun’s rays perpendicular to their location while other parts will receive them at an oblique angle. This sets up a differential temperature and thence originates the phenomenon of seasons.
For those of you interested, most planets have an axial tilt. Mars, Saturn and Neptune have tilt angles of 25, 26 and 28 degrees respectively. Mercury, Venus and Jupiter are near vertical while Uranus tilts at 97 degrees – almost horizontal. Of course, the terms horizontal and vertical are not necessarily that. It is only for ease in visualisation. 

Influence of Climate on Architecture

The Renaissance Period (14th to 17th Centuries CE) in Europe marked the beginning of intense scientific enquiry resulting in many discoveries and inventions in the western civilisation. The rate of advancement has been exponential to the point where we are now experiencing the effects of climate change due to global warming. 

In the exuberance resulting from advancement of technology, architects over the past few decades have increasingly neglected the basic laws of climatology while designing buildings. Consequently, we have examples of buildings completely clad in glass bringing in unwanted solar radiation which in turn increases the air-conditioning load and therefore the consumption of fossil-fuel sourced electricity. Poorly daylit buildings, badly oriented buildings, wrong siting, wrong materials and the like are all symptomatic of a design process that is disconnected from climate-conscious thinking.

Passive Solar Architecture

Passive Solar Architecture is a term that represents a set of principles and practices used to design and build in consonance with the climate of the site. At the minimum, it would help in reducing the user’s dependence on artificial means of achieving comfort in the building. An advanced approach would include using materials that are local in nature and use the least possible energy for its processing and transportation to the site. Some of the important parameters that govern comfort are as follows:
·       Protection from heat and cold
·       Sufficient daylight
·       Protection from precipitation
Let us take each of the above three aspects and break them down to passive solar techniques that could be deployed in design.

Protection from Heat and Cold

Thermal comfort of an occupant is one of the critical aspects that a building must provide for. In warm/hot climates the challenge is to keep the heat out and in cooler climates the challenge is to retain the heat within the building. Many buildings may have to deal with both extreme heat and extreme cold.

Orientation

Orientation of the building is one of the first aspects that an architect needs to consider. In most tropical areas, the major heat gain happens from the morning and the afternoon sun. Therefore, it would make sense to have as short walls possible on the eastern and western sides and have longer walls facing north and south. In colder zones, it would be best to expose the facades to portions that receive the most solar radiation in the winter. It is common practice to have larger and more open facades towards south as the most amount of solar radiation comes in at a low angle.

Glazing

The outer “fabric” of the building plays an important part in heat transfer from outside to inside and vice versa. As a thumb rule, a single layer of glass in a window or a curtain glazing wall transfers heat at double the rate of a wall made of 200mm thick solid concrete block or 230mm thick burnt brick wall. This means that in a warm climate, it would make sense to limit the amount of glass to ensure that there is enough light and ventilation. In colder climates, it would make sense to have larger amounts of glass in order to heat the building. Of course, an architect would need to consider orientation and also must be able to reduce glass on facades that receive a high concentration of summer heat.

Insulation

Sometimes, just having a thick wall may not be enough. One would have to layer the walls with insulation in order to reduce heat gain (in warm climates) and heat loss (in cold climates). Similarly, high performance glazing with low rates of heat transfer may be used where required.

Sufficient Daylight

Daylight is an important factor that contributed to user comfort. Adequate daylight reduces the energy consumption by way of not switching on the artificial lights during the day and also helps the occupant be better aligned with the changing times of the day and hence contributing to overall well-being and comfort. Daylight can be managed by orienting the buildings in a way that cuts down glare from the sun. Glare can also be managed by the right use of sun-shading devices. Keeping plan depths to an optimum size, use of skylights, light shelves and atria help in maximising daylight in a building.

Protection from Precipitation

Protection from precipitation namely rain and snow is also an important determinant of building design. Correct orientation of a building with façade protection on the windward side is critical. Walls and window openings need to be well protected. The roofs need to be designed to quickly evacuate the water.


In conclusion, it is time that we, as architects and building professionals, take concrete steps to take design buildings that are climate conscious. It is pertinent for us to understand in depth, the climate of the region that we are designing in. In short, it is time to reconnect to nature!

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