Dept of Energy on White Roofs and Energy Savings

In 2001, the Department of Energy commissioned a study on the effect of light-colored or white roof membranes on energy use at a large department store in Austin, TX.

The executive summary of the report stated that reflective roofs typically absorb less sunlight.  “Less absorbed sunlight means a lower surface temperature, which directly reduces heat gain through the roof and air-conditioning demand.  Thus, reflective roofs reduce a/c energy use, the degree to which primarily depends upon building type, level of roof insulation, plenum ventilation, a/c size and efficiency, and, of course, roof albedo,” the report goes on to say.

The goal of the project was to measure and document air-conditioning and energy savings from a large retail location with a roof that had been retrofitted with a reflective roof.

The study pinpointed five steps:

  1. Identify a building with significant potential to save on peak energy demand:  The large retail building that they selected had originally had a black rubber roof, which was replaced with white roof membrane.  The building also had moderate insulation and a highly inefficient HVAC system.
  2. Install instruments on the building and observe:  The team installed instruments to measure weather, temperatures throughout the different layers of the roof and the HVAC system as well as energy consumption.  The data was collected over an eleven month period, before and after the installation of the white roof membrane.
  3. Analyze the data that had been collected and create a statistical model:  The team created a model that compared pre- and post-retrofit energy use as well as outdoor vs indoor temperatures.
  4. Calculate daily savings and demand reductions:  The team used he stats model to determine the impact of the retrofit on overall power use and the amount that was saved per day.
  5. Lastly, a cost/benefit analysis:  The team compared the overall cost of the retrofit with the energy and cost savings gained from the white roof membrane.

Savings over the life-cycle of the new roof membrane were projected at $70,000 for the 100,000 sq/ft building, not including the rebate programs, which totaled over $80,000.  The retrofit came at the end of the black rubber membrane’s life cycle, and it cost $1.50 per sq/ft (or $150,000) for labor and material, a negligible difference in cost compared to simply re-coating with the black rubber which saved the building owner the entire cost of installation over the white roof’s life cycle.  That’s not including the reduced maintenance on the HVAC system.

These are the kinds of savings that NovaTuff Roof Coating Systems can bring our customers, and they are well-documented by government agencies who have long supported a move to a more energy efficient commercial sector.  Of course, this building was an ideal candidate for energy savings, but, regardless of whether or not your building realizes this level of demand reduction, our roof system has a number of benefits that make it the ideal choice for any retrofit.

Check out our life cycle cost analysis to see how much we save building owners on average.

Read the full report from the Department of Energy here.

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