The roof is part of the building envelope determining the energy you need to cool or heat your house. The roof determines how much heat or air can leave or enter the house, which affects cooling and heating energy. Some roofs are better at minimizing heating and cooling energy than others.
Below are a few roof aspects determining energy efficiency.
Roofing materials have different energy efficiencies; heating affects them in different ways. The roofing material determines:
- How much heat can flow outside from the house
- How much heat can flow into the house from inside
- How much heat the material retains over time
- How much heat the material reflects into the atmosphere
For example, metal roofing is energy efficient because it reflects most of the heat and doesn't store much of the heat it absorbs. Clay or slate tiles are energy efficient because they don't allow much heat to pass through and can retain much of the heat they absorb.
Roofing color matters because light-colored roofs reflect more energy than dark-colored ones. The light-colored roofs encourage energy efficiency in hot climates where you don't want the roof to admit heat into the house. The dark-colored materials are best suited for cold areas where you want to absorb and retain as much heat as possible in the house.
The roof design determines how much heat can penetrate or escape the house. For example, houses with eaves are more energy efficient than those without. The eaves shade the house and prevent direct sunlight penetration into the house. The eaves also shade the walls and prevent their heat absorption.
Proper ventilation allows hot air to escape the house. Roofs have different ventilation systems, such as soffit vents, powered vents, ridge vents, and cupolas. The main thing is for the ventilation system to match the house's capacity. Otherwise, hot air might take a long before leaving the house, lowering energy efficiency.
Like the roofing material, the insulation prevents heat exchange between the house's exterior and interior. During the hot season, roof insulation prevents heat outside the house from penetrating the house. During the cold season, the insulation traps heat inside the house. The insulation thickness and material determine its effectiveness.
Roof design and installation provide the baseline for energy efficiency. Remember to maintain your roof to continue enjoying its energy efficiency. Consult a roofing installation contractor to inspect the roof and fix emerging damages at least once each season.