A long-standing practice of architects is to utilize architectural metals as a sunshades to reduce glare, improve the quality of experience inside a building, and of course, reduce heat gain.
But how effective are these sunshade elements at reducing heat gain?
Expanded mesh’s role in reducing facility cost of ownership
Heat Gain Study and Assumptions
To answer this, AMICO Architectural Metal systems hired an outside engineering firm to perform a digital simulation to quantify the effects of expanded mesh as a sunshade. First, it is important to understand that every building will have a different set of variables that will impact heat gain results.
For this simulation, a digital 32-foot by 32-foot room with a large south-facing window with a heat gain coefficient of 0.46 was created. This digital building was then placed in an environment matching the meteorological and solar conditions of Los Angeles, testing hour by hour over the course of a typical year.
Simulation Results
The results were non-ambiguous and predicted meaningful heat gain reduction using expanded mesh as a sunshade when placed within 5 feet of the window.
When the window is covered 66% with APEX01 expanded mesh panels, 45% of the heat gain was mitigated. FIGURE 1 summarizes the heat gain reduction predicted under various levels of window coverage.
Interpreting the Results
To walk through the interpretation process, we will look at previously built project pictured here. The building is designed with a large south-facing wall of windows.
If we were to take this building plan and construct a duplicate in Los Angeles, what can we learn about the practical savings associated with the expanded mesh sunshade?
To make these calculations we will assume the following:
- HVAC coefficient of performance (COP) = 4
- The south facing façade has 9,000 sf of windows
- 0.46 solar heat gain coefficient
- California’s electricity cost is $0.25 per kWh.
- California’s PG&E produces approximately 0.542 pounds of CO2 per kWh
Knowing that the building’s south face is clad 66% with APEX03, our heat gain models estimate that the mesh is eliminating 15.72 kWh per square foot of glass per year from entering the building, or 141,513 kWh in total per year. Based on California’s electrical cost, APEX03 mesh façade would save the owners $35,378/year in HVAC energy use. Assuming building owners will renovate their building facades every 20 years, the expanded mesh façade will save owners over $707,000 during the life of the sunscreen–more than paying for itself. This electrical savings would also prevent an estimated 76,700 pounds of CO2 from being emitted each year, or and over 1.5 million pounds of CO2 over the life of the screen. To put that into context, this is equivalent to preventing 111,000 pounds of coal from being burned per year or roughly 2.3 million pounds over the life of the façade.
Beyond all the raw numbers and calculations, how do expanded mesh sunshades impact the architect’s design process?
Improved Occupant Satisfaction
Maximizing equitable access to daylight for all users of a facility is important. Expanded mesh can be a daylight control tool that still allows natural light deep into a space. Studies suggest that daylight has a direct impact on the well-being, productivity, and overall sense of satisfaction of users of a given space. Expanded mesh can play a significant role in the design and control of that light, even offering a tool for the designer to ensure quality through glare reduction.
Lighting Design
Expanded mesh sunscreens can open the design possibilities of including large expansive south-facing windows that deliver consistent, ample natural light into the facility, further driving down electrical lighting loads while still balancing and controlling heat gain.
Increased Access to Windows
For plans where municipalities or project specs are capping energy usage and driving design decisions, expanded mesh sunscreens can be a solution for deploying more windows in your design and creating a more open and pleasing environment for users to inhabit while minimizing heat gain that would otherwise drive down the window count.
Michael Nelson is in marketing and product development at AMICO Architectural Metal, Burlington, Ontario, Canada. To learn more, visit www.amicoarch.com.