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An Architects’ Guide To Exterior Shading Solutions

Top 9 things to know...

1. Exterior Shading Solutions and Sustainable Design

2. Introduction to Exterior Shading Solutions. 3. Benefits of Exterior Shading Solutions. 4. Common Myths of Exterior Shading Solutions. 5. The Passive House and Exterior Shading Solutions.

6. Exterior Shade Products. 7. Exterior Shade Fabrics. 8. Exterior Shading Controls. 9. Completed Exterior Shade Projects.

1. Exterior Shading Solutions & Sustainable Design

Why do we need a guide to Exterior Shades Shading Solutions? Because many in the architectural and design community view window coverings as an afterthought, and as a result, they may not give their projects the best chances for success. This statement is especially true with Exterior shades and their growing popularity in the US. Exterior shades have matured way beyond mere decoration and have become a significant part of today’s sustainable building systems.

Today’s emphasis on sustainable solutions has rushed window coverings to center stage with other building systems, such as lighting and HVAC. Architects and designers are becoming aware of the advantages of incorporating window coverings into their buildings and exterior shades into the building’s facade.

Sustainable Design The term Sustainable Design is commonly heard today and for most of us in the design community is challenging to define. The best definition comes courtesy of the American Institute of Architects (AIA), which says: Sustainable Design is a collaborative process that involves thinking ecologically, studying systems, relationships and interactions in order to design in ways that reduce stress to systems.

The question we need to ask is how do Engineered Shading Solutions reduce stress to systems? There are 4 critical areas where we can see this applying: 1. Energy–Reducing the amount of solar energy entering a space and there by lowering the amount of energy required for cooling. 2. Glare–The implementation of effective solar shading fabrics to cut down annoying glare due to excessive daylighting. 3. Light–Installing shading solutions that can filter or eliminate sunlight from passing through windows. 4. Sound–To lower the sound reverberations bouncing off the glass through the use of roller shade fabrics (interior applications only).

The premise of this guide is to dig deeper into the definition of Exterior Shading Solutions. What does it mean to be called a sustainable system? How does a system for exterior applications actually provide solutions for reduction of solar heat gain and annoying glare while regulating the amount of light into a space? Exterior Shading Solutions can be categorized into the following 3 parts: 1. Solutions – Solutions refer to the type of exterior shade selected for the project. 2. Controls – The second element of an Exterior Shading Solution is the controls. 3. Fabrics – The third leg of performance rests with the fabrics. The science behind the fabrics of an Exterior Shading Solution offers the ability of reducing solar heat gain, controlling excessive glare and regulating the amount of daylighting.

2. Introduction to Exterior Shading Solutions

Exterior Shading Solutions are in their infancy in the United States. Architects are now being introduced to the innovative European systems that provide superior performance for the reduction of solar heat gain, glare control and elegant design. All across the European continent (including northern climates) Exterior Shading Solutions are seen on the most sustainable buildings.

This Architect’s Guide to Exterior Shading Solutions provides the reader with a complete understanding of why one should consider an exterior shade in the first place, as well as seeing the range of possible solutions, choosing the correct fabric, checking out what’s required for controls and sensors. Exterior Window Shades are three times more effective at reducing solar heat gain then interior shades. That is why all across Europe in both northern and southern climates, we see Architects specifying and installing Exterior Shading Solutions for residential and commercial projects.

3. Benefits of Exterior Shading Solutions

The main reason Exterior Shading Solutions are gaining popularity is because of its superior performance in reducing solar heat gain. The graphic below tells it all. A space with no shades allows 80% solar heat gain to enter a space. An Interior Shading Solution offers better results blocking over 50% of the solar heat gain. However, for maximum results nothing beats an Exterior Shading Solution, which blocks over 85% of solar heat gain.

How do we control solar heat gain using exterior shading solutions? Once the system is selected, the next aspect is the fabric. Selecting exterior shade fabrics is different than choosing one for an interior installation. Since darker colors absorb light, which turns into heat, we know that could be a problem for interiors as the graphic below shows.

However, when the shade is installed on the exterior the heat absorbed by the darker fabric and is released into the atmosphere before it has a chance to penetrate through the glazing and into the space.

For this reason, we typically recommend a darker color fabric that performs better then lighter colors for exterior shades.

4. Common Myths of Exterior Shading Solutions

With the increase in popularity of exterior shades below are the four most common myths or misconceptions that architects and designers continue to inquire about when considering exterior shading solutions for their projects:

  • Exterior shades cannot survive stormy weather conditions

  • They must have a short life expectancy

  • Maintenance is problematic

  • Interior shades are more economical then Exterior Shading Solutions

Stormy Weather: High Winds - The number one concern I encounter is the issue with high winds. Yes, high winds could be a problem if an Exterior Shading Solution is not retracted before the high wind event occurs. That is why all Exterior Shading Solutions are installed with wind sensors. For example, the Cable Guided Exterior Solar Shade calls for the wind sensor to send a signal to its motor to retract when wind gusts reach 25-30 miles per hour. To give you an idea of how often that may occur, 35 mph is how a tropical depression is categorized. Between 39-73 mph is a tropical storm and over 74 mph we reach hurricane force winds. These wind conditions occur less than most people realize, but when there is a strong wind event, Exterior Shading Solutions are retracted to a closed position and protected.

Rain, Snow & Ice – A rain with winds less then 35 mph will cause no issue for an Exterior Shading Solution. However, it is recommended that during harsh winter days with snow and ice that the shades or blinds are retracted. Snow and ice can prevent an Exterior Shading Solution from functioning properly. Additionally, it is beneficial to have the Exterior Shading Solution retracted because solar heat gain entering the space during wintertime is beneficial in reducing heating costs. Life Expectancy As an exterior product, Exterior Shading Solutions are manufactured to withstand the elements are have a long life expectancy. Let’s break down the components:

  • Aluminum Extrusions – All the enclosures are extruded in aluminum and anodized to offer an extremely durable and long lasting finish. This process provides a very high resistance to corrosion.

  • Motors – Line Voltage shade motors have, over the past 25 years, proven to be very reliable and robust. We have removed old shades where the fabric has worn out but the motor was still working without any issues. Today’s basic line voltage motors while only warrantied for 5 years has the potential to last a quarter century or more without question.

  • Fabrics – The major manufacturer of fabrics for Exterior Shading Solutions is Serge Ferarri. They serve the Fabric Architecture community throughout the world with amazing durable and long lasting fabrics. There proprietary technology called Precontraint creates a fabric that won’t tear or stretch and is used on retractable roofs in stadiums worldwide. Our Exterior Shading Solutions use the same fabrics.

Maintenance Anything on the façade of a building needs some type of periodic maintenance. This is also true for Exterior Shading Solutions. However, in the planning of these systems, we intentionally design them with the lowest maintenance parts on the exterior. Let’s examine these external elements:

  • Aluminum Extrusions – There is no maintenance required for any of the aluminum extrusions except an occasional washing, which can be carefully done with a pressure washer. You do not want to spray under the enclosure that protects the roller, motor and power connections.

  • Cables – The 6mm cables need to be checked for tension occasionally.

  • Motors – The motor is the only part that may ever need to be replaced. The motor is located in the shade roller tube and is easily repaired.

  • Fabrics – The only maintenance ever needed on the fabrics is an occasional cleaning with soap and water.

  • Controls – Our controls are placed in a centralized interior location for easy programming and diagnostics. Based on dry contact signals, as opposed to data and software control, the system is easy to operate and maintain.

Costs This myth is my favorite to debunk. There is a wide held belief that Exterior Shading Solutions cost more than interior shades. This is not the case! The biggest jump in price will be from a manual system to a motorized system, however there is a very nominal price different between interior and exterior motorized solutions. The point is, is that if you are planning to do a motorized shade anyway, why not put it on the exterior where you can receive three times better performance and payback then an interior shade.

Conclusion The bottom line is that Exterior Shading Solutions by InSync Solar have been designed to deal with bad weather effectively and safely, have a long lifetime in service if they are maintained properly and cost no more than interior shades. The benefits include tremendous reductions on solar heat gain and a 3 times faster payback over interior shades.

5. The Passive House and Exterior Shading Solutions

The Passive House is designed to achieve maximum solar heat gain by orienting its largest windows with southern exposure with the intent of providing at least 50% of the building’s heating demand. While this works well in the winter months when the low angled sun radiates heat into the space, this solar radiation becomes excessive during the summer months and needs to be shaded. InSync Solar provides Exterior Shading Solutions with the needs of the Passive House in mind.

Even though exterior shading solutions are preferred, they may not be possible for a variety of reasons, such as, “we never planned for exterior shades, now it’s too late”, or “we don’t have a budget for motorized shades”, or just simply “we don’t want exterior shades, we want interior shade.”

This incredible performer has a thin metallized coating on the street side of the fabric. This allows the sunlight to reflect off the fabric and back out though the glass. The result from the reflective backing is low transmittance, highly reflective and good absorbance numbers.

6. Exterior Shading Products

Cable Guided Exterior Shade The cable guide exterior shading solutions is elegantly designed and very versatile for both residential and commercial projects. The aluminum cassette is powder coated in a range of standard colors or can be custom finished. The side cables are able to be mounted to the wall or floor as well as be integrated into the building façade.

The Cable Guided Exterior System is a motorized exterior window shade powered by 120v motors and can be functioned either with wired or wireless controllers. Wind and sun sensors are also offered and many times required. This system is an automated solution that can be integrated with any control system.

ZIP Exterior Shade The Zip Shade is a breakthrough design that is revolutionizing the window shade industry. It is called it a Zip Shade because a zipper-like locking device is welded to the fabric edges. The zipper slips into a side channel that keeps the fabric from falling out. The bottom hem-bar is weighted so when the shade is completely closed the fabric provides a drum like cover to the window.

With the fabric locked in, the Zip Shade offers multiple advantages. A typical problem with a standard Blackout Shade with side channels is that the fabric never stays in the channel. A simple push on the fabric, and the cloth pops out, leaving a wrinkled condition. The Zip Blackout Shade never allows for this to occur, which is great for bedrooms, hotel rooms or conference rooms.

The Exterior Zip Shade is where the performance soars. As an exterior window shade, the system blocks over 85% of solar heat gain. With the Zip feature, the system is very wind resistant. The fabric stays within the side channels with winds blowing at over 80 miles per hour. The Exterior Zip Shade also can be installed on patios where they provide excellent insect protection.

The ZIP system is a versatile Engineered Shading Solution. Powered with a line voltage motor, it offers not only solar heat gain and glare protection but also performs double duty as an insect screen. The aluminum headbox is available in white, bronze, black, ivory or silver finishes or custom RAL.

7. Exterior Shading Fabrics

Exterior Shading Solutions require fabrics that can withstand the elements as well as for certain applications, perform under constant tension. The best fabrics for Exterior Shading Solution are from Serge Ferrari. Their fabric uses the technology they call Precontraint. It is a high-tenacity polyester micro-yarn base cloth coating of the warp and weft threads under a high-performance polymer surface layer. This technique provides exceptional dimensional stability, long term strength and exceptional flatness. The Serge Ferrari fabrics can be seen on the London Olympic Stadium roof as well as many other prestigious projects worldwide.

The chart below offers some additional information.

This solar heat gain (SHG) chart is for the Soltis 92 fabric from Serge Ferrari. It is comparing white vs. black fabric for an exterior and an interior application. The white color allows 31% SHG when used as an interior shade and drops to 20% for an exterior installation. The black color however allows 69% SHG on the interior but jumps to an amazing 14% performance once mounted on the exterior. This is due to the 91% absorbance, which dissipates into the atmosphere.

Visual Transmittance – Selecting an openness alone based on orientation may lead to disappointment. The color of the fabric plays a role in the amount of light entering a room. This is called visual transmittance. To compare, take the same fabric with the same openness, one in white and one in black. The white color brightens the room more than the black, because the darker colors will absorb more of the light. Therefore, choosing a fabric based on openness alone may not provide the desired solution.

Glare ControlGlare is caused by a significant ratio of luminance between the visual task and the glare source. A solar shade will reduce the disparity in light levels as in between a computer screen and a window.

To understand the cause of glare, let’s take a look at the 1-3-10 Luminance Ratio Rule. This means that the light level between the visual task and an adjacent surface needs to be less then 1 to 3. The light level between a visual task and a non-adjacent surface should fall within a 1 to 10 ratio.

In the photo below, the room without an Interior Shading Solution, the light levels fall way beyond the 1-3-10 Rule with the result being glare. However, with glare reducing fabrics, the levels are corrected and the glare is reduced by as much as 95%.

Let’s compare the same fabric in the same colors as our previous example on solar heat gain control. A white color 5% open fabric will reduce glare by 57%, while a black color fabric reduces glare by 90%. So clearly, the darker color has a significant advantage on reducing glare then light colors, since the darker color absorbs the light.

Transparency – One of the benefits of solar shade fabrics is the transparency or the ability to see through the fabric itself. Of course, this transparency is regulated by the openness, but it is also determined by the color. In the picture below, the top row is white color fabric in a series of openness of 1, 3, 5 and 10%. The bottom row is the same arrangement of openness. Clearly the black color provides better transparency then the white color.

The ability to see through the fabric is an advantage of solar shade fabrics. It is important to remember, that there is a tradeoff between seeing through the fabric with a larger openness in exchange for allowing too much solar heat gain.

Finishes – Choosing an aluminum finish plays a role in shades, blinds and rolling shutters. On the Exterior Cable Guided and Exterior ZIP Shades the headbox, side channels and hem-bar are aluminum and are available in standard colors. However, custom finishes are available. The RAL color matching system is the industry standard for identifying precise colors.

8. Exterior Shading Controls

As you have read so far, exterior motorized shades provide the ultimate solution where heat and glare control are needed while preserving the view. Many European countries are now mandating exterior shading on all new building projects. The US is rapidly embracing this concept and exterior solar shading will become a commonplace solution set for most architects and designers.

The challenge of selecting a control system design is often hampered by a lack of knowledge and manufacturers who do not fully understand the limitations of the equipment they are proposing. There is a fundamental difference between the actual equipment selected and how it is configured and laid out. In short, the equipment is not the control system. It is just one element in the overall design. Use the following checklist as an aid to smarter exterior shading designs. Engineered shading consultants should be an essential part in the overall design process and will add value to the finished project.

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