air conditioning for hot climates

The use of air conditioning in hot climates is increasing at high rates. But this isn’t an energy-efficient option or an environmentally-friendly one…

The only explanation to the huge increasing of air conditioning is simple: inadequate home shading and orientation, inadequate home ventilation and sun control, low levels of insulation and poor design features...

When to use air conditioning in hot climates

Well designed homes require little or no air-conditioning, whichever the climate. And even when AC is advantageous or justifiable, it should be used and installed carefully, within a proper design approach.

Otherwise energy bills will soar. If you are building a new home, or remodeling, pay attention to some basics, concerning home design and air conditioning.

Design approach for air conditioning in hot climates

An air-conditioned home requires a specific design, largely based on insulation, small sized windows and small rooms… Large rooms with great height will demand high levels of air conditioning.

Air conditioning & Air infiltration

Minimizing external air infiltration and heat gains is crucial in any cooling strategy based in air-conditioned. To achieve it, there are three main elements or strategies:

- Shading strategies (they may include very different elements: overhangs, awnings, trees, etc).
- High insulation levels in walls, ceiling and floors (insulation is crucial to cut heat gains). The walls of the air-conditioned rooms should also use a vapor barrier (installed between the insulation material and the warm humid air…). Some strategies use low mass construction materials to facilitate a quicker cooling.
- Reduced glass areas: windows should be small enough, tightly sealed and with the right type of glass.

Home orientation

To get low heat gains and ventilation you should consider a good orientation to the breezes (and, in hotter climates, also to get sun protection).

See: Home Orientation

Combining air conditioned rooms with natural cooled ones

In hot climates, air conditioning the whole house can be too expensive. To reduce energy bills, do not install air conditioning in the less used rooms and parts of the house. Apply it only where thermal comfort is important, and use fans and ventilation in the non-air-conditioned parts of the house..

See: Floor Plan for Cooling

Fans and ventilation

The use of fans isn’t incompatible with air conditioning as long as they run in different times. That is: you may run air conditioning during some time (say, an hour) in a closed room. And then (once the humidity levels are sufficiently low, in the case of hot-humid climates) use fans instead of air conditioning, to get thermal comfort.

See:
Window Fans for Cross Ventilation
Fans and Cooling
Fans Usage
Ceiling Fans Basics

Type of AC, thermostats and sensors

Use programmable thermostats, sensors and timers to reduce the use of air conditioning.

Also prefer ductless split systems and room/window air conditioners (instead of central air conditioners). In hot humid climates, prefer de-humidifier air-conditioners.

Adapt your lifestyle

Air conditioning should be used parsimoniously. We shouldn't isolate our homes and ourselves from the surrounding environment. Our lifestyles should adapt to the external conditions and take advantage of the periods of comfort that they provide, minimizing the use of mechanical air-conditioning.