CUSTOMER STORY

Cascadia Windows & Doors leverages VitalMetrics to compare the environmental performance of various window frames

Background

Window systems play an important role in determining the environmental and energy performances of a building. Energy losses through windows demand additional heating or cooling to maintain desired internal building temperatures, which in turn increases energy costs and greenhouse gas (GHG) emissions associated with the additional heating or cooling needs. One major contributing factor in the overall thermal insulation performance of a building is the window frame material selected.

In a study commissioned by Cascadia Windows & Doors Ltd., VitalMetrics found that fiberglass window frames conserve 68% more heating and cooling energy than typical vinyl (PVC) window frames, and conserve 87% more energy than thermally-broken aluminum frames (Figure 1). This can translate to increased costs for users, but what environmental impacts do these additional energy needs create?

Results

While the difference in annual emissions between fiberglass and PVC frames is less than 3 kg of carbon dioxide equivalent (CO2eq) per square foot of frame, these emissions are more substantial when scaled up to an entire structure. Considering a typical high school building with 400 PVC windows, the annual GHG emissions mitigated by retrofitting all windows with fiberglass frames is about 1.6 metric tons CO2eq, which is about the same as combusting an additional 180 gallons of gasoline per year.

When purchasing window frames, other important factors to consider are the frame service life and energy performance over time.

FIGURE 1: ANNUAL PRIMARY ENERGY LOSS PER SQUARE FOOT OF FRAME SURFACE AREA

FIGURE 1: ANNUAL PRIMARY ENERGY LOSS PER SQUARE FOOT OF FRAME SURFACE AREA

FIGURE 2: LIFE CYCLE PRIMARY ENERGY CONSUMPTION OF ONE WINDOW FRAME, INCLUDING EMBODIED ENERGY, USE PHASE ENERGY LOSS, AND END-OF-LIFE MANAGEMENT ENERGY REQUIREMENTS.

FIGURE 2: LIFE CYCLE PRIMARY ENERGY CONSUMPTION OF ONE WINDOW FRAME, INCLUDING EMBODIED ENERGY, USE PHASE ENERGY LOSS, AND END-OF-LIFE MANAGEMENT ENERGY REQUIREMENTS.

On average, aluminum window frames have a service life of about 40 years while PVC frames last about 22 years. Fiberglass window frames boast a service life of more than 80 years, meaning two aluminum frames and four PVC frames are needed to do the same job as one fiberglass window frame. Not only does this increase replacement frequency, but the primary energy needed for the manufacturing of new frames and disposal of old ones also increases. Over the course of its life cycle, the primary energy consumed is far less for fiberglass frames than either PVC or aluminum, with PVC consuming the most energy over the 80 year period due to its short service life and relatively high embodied energy (Figure 3).

If all 37,100 high schools in the United States each had 400 windows and were to switch from PVC or aluminum window frames to fiberglass frames, the total amount of direct energy saved per year would be about the same as the natural gas energy consumed by about 38,000- 115,000 households in the state of Washington each year.

Conclusion

VitalMetrics concludes that fiberglass frames exhibit superior thermal and durability performance, contributing to a longer service life and decreased energy consumption compared to aluminum and PVC frames; the use of these frames presents opportunities for cost savings and reduced environmental impact. These findings indicate that adopting fiberglass window frames on a large scale may have a substantial impact on overall building efficiency.