The urban island effect is a heat phenomenon prevalent in all urban areas. Could it work in Sherman Oaks?

It results in a major temperature difference between high-density urban areas and the surrounding countryside. The primary cause of this phenomenon is the large expanse of impervious reflective surfaces on urban homes – they absorb solar radiation, retain it as heat, and transfer it to other hard surfaces through radiation and conduction.

If You Have Cooked Something in a Microwave

Crudely speaking, you can think of the urban island effect like microwaving an air-conditioned home. The urban area is the rotating plate inside the microwave and the solar heat are the microwave radiations. The only thing missing is the smog of particulate matter that gets dispersed into the atmosphere because of convection currents generated by heat waves. Throughout the day, a home’s walls, roofs, and floors are bombarded with this heat energy and since the internally cooled air usually comes in contact with all these surfaces, it gains heat energy via convection.

The Costly Consequences

As a result of the heat island effect, homes retain more heat energy – and the air conditioning units, in their efforts to condition the internal air to acceptable thermal comfort levels, utilize ever-greater amounts of energy. More energy equals higher bills – and people have begun looking for natural ways of reducing the heat signature of their homes. Roof gardens are a great way to reduce the energy costs of maintaining a comfortable interior air quality and temperature.

Roof Gardens – The Green Energy Savers

What is a roof garden? It is simply any garden on the roof of a home that is intended to bloom throughout the year. Its primary utility is its usefulness as a temperature control tool in urban settings.

A roof garden acts as a heat sink for the home – the plants reduce the overall heat signature of the home by absorbing the solar energy, utilizing it for sustaining themselves, and dissipating the excess energy through perspiration of water. Both of these actions prevent atmospheric radiation from getting absorbed by the home and hence reducing the heat transferred to the internal through home walls, floor, and rooftop.

Roof Gardens as Natural Ventilators

Reducing direct contact between the conditioned air and solid surfaces is essential for reducing energy costs of air conditioning a home. This is because conduction causes the maximum transfer of heat energy from outside atmosphere and the inner conditioned air.

A roof garden is a natural ventilator for the home as it serves a dual purpose:

  • It absorbs solar radiations and atmospheric heat,
  • Filters gaseous pollutants and toxins from the air

A roof garden not only reduces the heat absorbed by your home’s surfaces but also dispels dust and airborne particles.

As a result, your air conditioning unit’s efficiency dramatically increases as it will only have to condition the air and spend far less energy removing heat from the air.

This article was provided by American AC Heat Plumbing. Since 1981, American Air has been providing professional air conditioning and heating service and repair. Check out their $99 tune-up special – good for your air conditioner or furnace!


James Smith

As you can tell from our humble beginnings in 1981, we began as a family-owned business and stayed a locally owned air conditioning and heating company in Los Angeles county for nearly 40 years.