Delivering energy efficient architecture in warm climates is an interesting challenge. Apart from structural integrity and aesthetic appeal, architecture is also about the comfort of the people occupying the home. A key aspect of comfort is temperature modulation- after all, in the most basic sense, a house is built to protect us from the extremities of weather. While appliances such as air coolers, conditioners and fans are highly effective in cooling down homes, they consume a lot of energy. Architects need to double up as visionaries and plan to manage temperature through design & structure. Here are some key tricks in architectural design which can help keep homes cool.
This is an essential first step, where an architect needs to sit with the client and assess. It requires a whole-system approach, where client and designer, understand the future functioning of the house. List out the home electronics and appliances that would be used. Understand from the client, their functional prerogatives.
For example, do they need space for reading, is an outdoor patio okay with them and the type of lighting they are comfortable with. Note down their water heating requirements, and the types of doors & windows they are comfortable with. Most architects skip these steps and jump onto providing clients with a good-looking home design. However, if you want clients to appreciate your work 5-10 years down the line, a thorough evaluation is essential.
To manage light and heat in a natural way, it is important to understand the movement of the sun, on-site. The direction of the sun changes daily and seasonally. Orientation of the building matters.
A house with windows facing the east & west, can experience up to three to five times more heat. Between east and west, having window exposure in the east is preferred, as the west gets sun exposure during the hottest times of the day. Plan in a manner that you modulate natural sunlight and heat to your advantage.
Most architects are tempted to use most of the area available on-site for construction. However, it is important to leave a reasonable zone around the house to achieve an energy efficient architecture. Allocate this zone for shrubs, plants and trees. In the future, these very trees will become natural cooling umbrellas.
Pavements are a key part of landscaping- but they tend to reflect heat & warm up the house. Ensure pavements are shaded too. Outdoor seating is a good idea, if covered well with shades. Consult with your client and understand if they are an “outdoorsy” family. Converting a few rooms into an outdoor format can cut down energy costs and if designed well, such areas can be surprisingly cool.
There are two ways to do this. First is the horizontal airflow, better known as cross ventilation. Plan for same sized windows facing each other on opposite walls. This creates a mechanism where air that is sucked into the house is also pushed out of the house. There is no stagnation of warm air.
The second way is the stack effect method. Simply put, hot air that rises from a room, is let out through the roof. This creates a vacuum for cool air to be sucked in through the windows, ensuring a naturally cooled house. This cyclical motion can be created placing slit like windows, just below the ceiling line. A roof window vent is also possible, however, ensure that a directly overhead sun does not cancel out its effectiveness.
Clients usually believe that insulation increases heat, however as an architect you need to create awareness. Building materials can resist thermal energy and this is denoted by their R-value. Architects can use advanced framing methods that can create space for insulating material between wood and steel.
For exterior walls, exterior rigid insulation is highly effective and is done using materials like mineral wool, expanded polystyrene and phenolic resin. Ensure you use materials with low global warming potential (GWP). Roofs can be insulated using methods like closed-cell spray foam, blow-in insulation and rigid foam boards.
Next, is the insulation of the interior walls, windows, ceilings and floors for achieving energy efficient architecture. This is easier to do, even post construction. Such insulation helps prevent air drafts and seals up gaps, from which heat can enter the house. Insulation material can be smartly used to lock up such gaps, making the house cooler.
The role of windows in energy efficient architecture, is quite underestimated. In hot climates, heat tends to flow in through the window frames rather than the glass. Very unlikely, but true. So, it is better to create few large sized windows rather than multiple small ones. This is because the glass to frame ratio in large windows is high.
Some architects choose fixed windows in rooms, where air conditioner usage is required. Fixed windows prevent heat leakage. However, for operable windows, try to make them in the form of casements or awnings. They are more airtight compared to single hung windows or sliding windows. Tinting of windows is a great way to keep the heat out. External overhanging awnings help with added shade. But make sure you optimize this against the amount of natural light required to be let in. Sizing it right, is key.
Painting the roof in light, reflective colours is a great way to create energy efficient architecture. Same applies to external and internal walls.
Architects have also begun using materials such as insulated hollow concrete blocks and clay pipes in construction. In the last few years, there has been an increase in adaptation of solar panels in energy efficient architecture. While expensive at the outset, over time, they reduce operative cost of energy consumption.
Clients, upon occupancy, can do multiple things to make their home energy efficient. From using star rated appliances and power saving bulbs, to reducing use of air conditioners and using fans to circulate cold air. However, it is an architect’s responsibility to create a house which is intrinsically cool. As one can see above, a few steps go a long way in creating energy efficient architecture. And it is just as easy to keep updating this knowledge bank, so that you can keep building homes with great functional value.