People who live in Florida or Texas often accuse energy-efficient campaigns and experts on their biasedness. And the fact of the matter is that they are right (most of the times). A lot of publishing material, awareness campaigns and most energy-saving tips are written with cold-climate building in mind. And perhaps righteously so, as supported by various results revealed by Department of Energy stating that Americans spend about twice as much for residential heating as they do for cooling.
Whatever the origins may be for the passive cold climate bias, it’ time to address the issue and discuss a few tips for the hot-climate design tips.
Before we move on to discuss designs aspects of the building built in hot and humid weather, it will be more beneficial to consider the factors, which influence this change. In hot, humid climates, the majority of the energy used to make the house comfortable is spent on cooling and dehumidifying the house. Houses must be insulated and sealed to try to keep the heat and humidity that surround the house from getting into the house. Think of it this way, you have a bowl filled with water, and you increase the flame heating it. What will happen as you increase the temperature? The water will start evaporating. Now project this same concept on a broader level. The hotter the temperature and the higher the humidity, the more there is a natural force driving the heat and humidity into your cold and relatively drier home, as compared to the atmosphere around it.
However, heat radiation should be your biggest concern in such a climate. Why? Well to put it simply, the sun’s rays directly heat up the surfaces of the house, and that heat conducts to the inside. If you have ever stepped on black asphalt or gotten into a car during a Texas summer, you have experienced how an object sitting in the sun can heat up much more than the ambient air temperature. Unlike good old days, the majority of the builders know what they are doing and are aware of the reality that house designs need to be climate-specific. And mentioned earlier, houses in areas where air conditioning bills are higher than heating bills are designed to reject exterior heat.
So, now you must be wondering: what are the most important factors governing hot-climate design?
While cold-climate designers have to worry about heat escaping from the envelope in all directions, the heat-gain concerns of hot-climate designers are overwhelmingly dominated by just three major factors: windows, ceilings, and internal gains. Experts are R-Control reveal, on summer afternoons, one large west-facing window with the wrong type of glazing can make a huge difference in a home’s heat gain.
Air leaks not only increase a home’s sensible cooling load; by introducing humid exterior air, they also increase a home’s latent cooling load, making the air conditioner work harder to wring moisture out of the air. Tight houses are much easier than leaky homes to keep cool and dry.
Over the past few decades, the increasing environmental concerns have contributed greatly in raising awareness for lowering energy costs. As a result, more eco-friendly and intelligent products have been introduced to cater the needs of people. Furthermore, in this aspect Useful hot-climate research has also been conducted by engineers from the Building Science Corporation; much of this research has been funded by the Department of Energy’s Building America program. The following list is a compilation of the findings of this study.
- Orient the home with long axis east-west.
- A slab formation should have a perimeter insulation but no sub-slab insulation.
- Shade is good. Roofs should have wide overhangs, ideally 3 feet wide or more full. Hurricanes like to grab onto roof overhangs, though, so be sure to secure roof trusses or rafters to top plates with adequate hurricane clips. Since a hipped roof can shade all four sides of a house, hipped roofs are preferable to gable roofs.
- Minimise East-West windows, as they are in direct sight of the sun for the majority of its path and thus contribute a lot in generating a lot of heat by allowing the sunlight to pass through them.
- Shade every window. Since the atmospheric hotness will be a lot higher as compared to colder environments.
- Ceilings and Roofs should be at least R-30
- If the house has an unconditioned attic, it is advised to insulate it.
- Wall insulation is much less crucial down south than it is up north; building with SIPs will do the job, or you can always go with other insulation techniques. If the house has concrete-block walls, install the insulation on the exterior, not the interior.
- Use ceramic floors.
- Try to use more modern lighting options (LEDs or CFLs) instead of conventions bulbs and rods, as they generate a lot of heat.
- Make a vented cavity directly under the roof. This allows a lot of the heat to be reflected and dissipated before it even gets to the ceiling insulation. Think of how much cooler it is under a canopy or tree than in the direct sun. Like a canopy, a vented roof shades the rest of the house.
- Pay particular attention to remedy thermal bridging if you are going with the conventional insulation techniques. SIPs, Insulated Panels and other such products are designed to reduce this issue.
- Although many of these suggested measures may seem obvious, they are widely ignored. Driving around Las Vegas, it’s easy to see hundreds of new homes with stingy roof overhangs and unshaded windows exposed to the full glare of the Nevada sun.