Cool Roofing Solutions

If you're not using a cool roof, you could be losing more than you think. Five truths to ponder.

Cool roofs can help save you money on energy bills* in the North as well as the South. Here are some cool truths to ponder when planning a new roof.

Truth 1: It's all about reflectivity.

A cool roof reflects the sun's energy, reducing rooftop temperatures. While a sunlight-absorbing black roof can reach up to 190°F in the summer, a reflective roof's temperature can be as much as 60°F lower. Dark surfaces also contribute to the urban heat island effect.

A cool roof reflects away the sun's solar energy, unlike a dark roof which absorbs it and transfers heat to the building below.

 

*Energy cost savings are not guaranteed and the amount of savings may vary based on climate zone, utility rates, radiative properties of roofing products, insulation levels, HVAC equipment efficiency, and other factors.

HEATING & COOLING DEGREE DAYS:

These units of measure describe how far the average daily temperature varies from a baseline of 65°F. Temperatures greater than 65°F are cooling-degree days, because we need to cool the environment back to 65°F. Heating-degree days occur when the temperature falls below 65°F.

 

 

TRUTH:

A cool roof reflects the sun’s energy, reducing rooftop temperatures. While a sunlight-absorbing black roof can reach up to 190°F in the summer, a reflective roof’s temperature can be as much as 60°F lower – reducing heat flow through the roof system.

GAS vs. ELECTRICITY:

On average, electricity costs up to 4 times more, per BTU, than natural gas. Not only is electricity more expensive than gas, but the rate structures are more complex. Seemingly small increases in electricity use can result in large additional costs due to the compounding effects of time of demand charges based on a few peak minutes of electricity usage during each billing period. 

TRUTH:

If your building uses electric air conditioning and natural gas heat, a cool reflective roof can help lower your energy bills* no matter where you are in the continental United States (including Northern States) by reducing the amount of air conditioning needed. How much could you be saving on energy bills? Find out by trying out our CREST energy calculator.

DEMAND CHARGES:

Simply put? Demand charges are the immediate usage put on your energy system. Some electric companies charge commercial and industrial buildings a demand charge penalty based on a few peak minutes of electricity usage during each billing period. Buildings that use the most electricity at one time often get charged the largest penalty, which can be up to 30 -70% of their total electricity bill. Air conditioners, by their nature, surge electricity demand at peak times of the day. Cool roofs can help reduce the air conditioning needed by your building by eliminating the extra heat that would be absorbed by a black roof.

TRUTH:

Dark roofs increase the need for air conditioning. They not only drive up monthly electricity-consumption costs, they can significantly increase demand charges as well. Less demand can mean less money spent on energy.*

A BLACK ROOF COVERED IN SNOW IS WHITE:

Your roof’s impact on your energy bills is based on the amount of sunlight reaching it, not on the ambient temperature. So even in regions with more “heating degree days” than “cooling degree days” a reflective cool roof will offset more hours of sunlight in summer than a dark roof can absorb to heat the building in winter; almost twice as many at the solstices. And, of course, during those long winter nights, sunlight is having no effect on your roof at all. Add to that the fact that a dark roof covered in snow is, effectively, a white reflective roof.

TRUTH:

A snow-covered black roof reflects the sun's rays but in the summer, it becomes a heat-absorbing sponge.

 

A PROPERLY DESIGNED ROOF REDUCES THE RISK OF CONDENSATION:

A properly designed roof can offset condensation in a variety of ways, including using multiple layers of insulation with staggered joints, installing GAF SA Vapor Retarder, or installing a fully adhered system, to just name just a few options.  

Adding layers of insulation can significantly reduce airflow to the dew point, helping to prevent condensation.

For example, improper insulation design may cause condensation, whether the roof is a cool or dark membrane.  

Always consult with a design professional to design a roof system.

 

Single layer of insulation:
A roof system designed without the proper amount of staggered insulation can have condensation issues regardless of membrane color.

Double layer of insulation with staggered joints:
A roof system designed properly will help reduce the risk of condensation regardless of membrane color.

COOL ROOFS ARE CHANGING THE ROOFING INDUSTRY:

Commercial buildings are benefiting from cool roof savings throughout the USA, even in Northern climates, and that is fundamentally shifting the roofing marketplace. For example, EPDM was the most popular single-ply membrane in the industry in 2003. Today, TPO makes up over 50% of the single-ply market. 

GAF offers a wide range of cool roofing technologies including... 

Single-Ply – available in both TPO and PVC, single-ply membranes are the most commonly installed roofing technologies due to the speed of installation and the variety of systems available.

  • EverGuard® TPO
  • EverGuard Extreme® TPO
  • EverGuard® Freedom
  • EverGuard® PVC

Asphaltic – available in BUR, APP, and SBS, asphaltic systems are great, time-tested multi-ply systems that can be installed in a variety of systems:

  • RUBEROID® EnergyCap BUR 

Coatings – available in acrylics, silicones, urethanes, PMMAs, and PVDFs, the GAF line of coatings can preserve and restore existing roofs:

  • Roof Mate Elastomeric Roof Coating
  • Diathon® Acrylic Elastomeric Roof Coating
  • Unisil Silicone Roof Coating
  • Kymax PVDF Fluoropolymer Roof Coating
  • HydroStop® PremiumCoat® Breathable Acrylic Membrane System

*Energy cost savings are not guaranteed and the amount of savings may vary based on climate zone, utility rates, radiative properties of roofing products, insulation levels, HVAC equipment efficiency, and other factors.