Residential green roof refers to the space created right on top of the household's roof for the purpose of vegetation and plants. These vegetation and plants provide an all natural insulation as well as shield the roof from direct sunlight, thus cutting down the use of air conditioning and ensuring the durability of the roof. Couple this fact with the over 100° temperature reduction that the residential green roof can impact on your home, it is an effective utility bill buster.
The money-saving nature of residential green roof can never be overlooked. Factors such as the type of vegetation you plant, weather condition and size of your roof will all decide on the exact amount you will be able to save. Authorities in Switzerland, Austria, France and Germany have long endorsed and encouraged the building of residential green roofs.
Recently it has also been recognized as an important factor in storm water management. Its ability to hold water prevents water (and pollution) from overflowing into the city areas and reduces the effect of city heat island effect -- a situation created by new urban planning with houses being built close to one another -- through the process of evapotranspiration (water evaporation from the plants to atmosphere) and shading.
Heat Island Group which is based in Los Angeles estimated that rooftop-cooling can bring about an annual savings of $16 million on your energy bills to both businesses and residences. According to the United States Department of Energy, green roofs and other reflective roof types, are capable of cooling New York City by 3.6°F. Not all buildings are ideal for residential green roofs; those with inadequate load factor (which means the roofs are not able to carry the weight of the vegetation on top), steeply sloped roofs as well as certain homes designs may be unsuitable for such implementation. It is important to consider factors like how much sunlight your roof is exposed to and the type of vegetation to plant.
Make it a necessary step to discuss with both a landscape designer and structural engineer before any architectural plans are developed. A structural engineer can advise you on how the piping runs and what waterproofing approach to take.
The cost of a green roof implementation can vary a lot depending on your existing roof, and the size and scope of your intended green roof. Typically material and labor contribute quite a significant portion of the budget.
Because lighter shades (versus the darker shades) are more adept to reflect sunlight away, it may be desirable to choose a lighter color scheme for your roof. And your choice may help to reduce the effect of urban heat island -- whereby simultaneous heating of hot roofs in an overly congested urban area will bring the temperature up a few notches.
White roofs can be used to more effectively cool steeply sloped roofs and reflect sun heat away. It is simply a coating not unlike any thick white paint but it will stay for 20 years. Application cost varies based on scope of job as well as the condition of your roof.
Certain utility companies offer discount for cool roof installation, make sure you check that out.