CRF1: The Impact of Buildings on Energy Usage
According to the U.S. Department of Energy, nearly 40% of total U.S. energy consumption and approximately 75% of all electricity consumption happens in residential and commercial buildings.
Improving energy efficiency makes it possible to lower building operating costs, lower CO2 emissions, and increase the ability to better control the indoor environment.
In fact, due to the high use of energy by buildings, code bodies, city and state regulators, and other organizations that regulate or influence building design have focused their efforts on requiring greater energy efficiency.
Regulations and codes that regulate building energy efficiency are generally aimed at increasing the use of:
- Higher insulation levels
- Reflective roofs
- Building air tightness
- Increased HVAC efficiency
- Energy efficient windows and lighting
How important is low-slope roofing to the nation’s energy efficiency?
According to the Center for Environmental Innovation in Roofing (CEIR), the low slope roof market in the U.S. in 2010 was approximately three billion square feet. Existing buildings account for more than 2.5 billion square feet of that total. That means the re-roof market has approximately five times the potential impact on energy efficiency as new roof construction!
Unlike structural assemblies or cladding, roofing will likely be replaced during a building’s lifespan – possibly many times. This makes roof design for improved energy efficiency very important for re-roofing of existing buildings.
The chart below illustrates significant improvements made in building efficiency in this century.
Heating, Air Conditioning, and Ventilation
Three roof properties significantly impact building energy efficiency:
- Membrane reflectivity determines the reflection or absorption of the sun’s energy, which is especially important during the summer and/or in southern locations
- Insulation affects heat transfer from the outside to the inside during summer and/or in warm climates, and from the inside to the outside during winter and/or in cold climates
- Air barrier systems regulate airflow between conditioned and unconditioned spaces.
Approximately 44% of the total energy consumption of commercial buildings is dedicated to controlling the indoor air quality and temperature. That includes space heating (25%), ventilation (10%) and cooling (9%). (Note, this is calculated in terms of British Thermal Units, BTUs, and not the cost of that energy. The relative cost difference between heating and cooling will be discussed in a later post.)
Commercial Roofing Fundamentals — An introduction to commercial roofing concepts
For commercial roofers, building owners, specifiers, managers or residential roofers considering moving into the commercial space, this blog series provides an overview of some of the key concepts that are driving industry decision-making.