By Justin Joseph
Automated solar shading systems are practical applications used by European architects and building owners for decades to substantially reduce building energy usage and increase natural daylight. Worldwide, many of the most sustainable and greenest buildings (i.e. high-performance and net-zero structures) use automated solar shading. Now, building owners and architects in Canada are becoming aware of the many advantages.
In its simplest form, solar shading is any device that excludes sunshine from a building—treatments such as curtains, awnings, and blinds. These assemblies control the amount of heat and light admitted to a building, helping maintain a more even temperature, despite varying climate conditions. Consequently, solar shading devices can provide energy savings by not only reducing the need for heating or air-conditioning, but also lowering reliance on artificial lighting. Additionally, they can decrease glare in interior spaces, improving visual comfort for those in the building.
There are many different types of solar shading products, ranging in function and sophistication. The technology has evolved from passive or fixed systems, to automated, intelligent systems that maximize daylight, reduce glare and solar heat gain, and provide optimized comfort for occupants. They are also energy-efficient in themselves—they only deploy when needed based on internal and external weather conditions.
There are many terms used to describe these assemblies, such as architectural blinds, motorized louvre blinds, venetians, and bioclimatic façades. Descriptors like operable, motorized, intelligent, or controllable, are also employed.
In North America, there are two major types of external automated shading—motorized retractable external venetian blinds (EVBs) and non-retractable motorized dynamic solar façades—the low-profile and monumental options, respectively. Both types are engineered to effectively control the sun at all times and on all elevations. They use intelligent control systems that automatically track the sun and position its blade elements to block direct glare, while allowing natural daylight into the interior of the building. For esthetic purposes, these systems come in various blade options, colours, and designs.
Benefits of natural daylight
Studies have shown people and businesses derive substantial benefits from natural daylight.1 For example, in schools, students exposed to natural daylight show improved student test scores, attendance, and health. With offices and factories, daylight improves concentration, productivity, and attitude of employees—this can positively impact the bottom line. In retail, sales are stronger in naturally lit areas where customers tend to stay longer. Additionally, the colours of products are vivid and true, making goods appear more attractive.
In healthcare facilities, natural light helps people feel better and aids in the healing process. In hospitals, studies prove the recovery rate of patients accelerates when they are exposed to daylight.
The Jim Pattison Outpatient Care and Surgery Centre (Surrey, B.C.)—designed by Kasian Architecture Interior Design & Planning Ltd.—uses natural daylighting for the benefit of the patients and staff.2 Patients waiting for a procedure are likely to feel stressed, and natural views out windows are calming. As well, the doctors and staff show better performance in operating rooms with windows.
Addressing solar heat gain
To be familiar with the benefits of natural daylight is one thing, but taking it one step further to understand solar heat gain is critical. (For a quick refresher, see “Solar Heat Gain: A Glossary.”)
Solar heat gain greatly impacts commercial energy use; more than half (i.e. 57 per cent) of a building’s energy usage is affected by façades (including lighting, space heating/cooling, and ventilation). In other words, radiation transmitted from the sun can have an enormous influence on heating and cooling requirements. The sun often makes perimeter spaces uncomfortably hot, creates glare, and fades fabrics. The advancements in glass technology have helped to minimize solar radiation, but usually at the expense of light transmittance.
With typical heat gain profiles using clear single glazing and clear double glazing, approximately 82 per cent and 70 per cent (respectively) of solar heat passes to the interior. (These figures include re-radiated heat that is absorbed in the glass, along with, to a smaller extent, ground-reflected heat). With automated solar shading, building owners (or tenants) are able to use a glass with high visible transmittance (VT) to increase daylight-harvesting and reduce solar heat gain.
In a closed position, exterior blinds virtually eliminate solar heat gain (i.e. bringing it down to 0.2). Without any blinds, 60 to 80 per cent of the sun’s rays penetrate the glass. Interior blinds, while an improvement, still allow the sun’s rays to penetrate the glass and heat the interior space. Exterior-mounted blinds, on the other hand, are seven to 10 times more effective than interior blinds in minimizing solar heat gain.
As an integral part of any building façade, external venetian blinds can be the single most important exterior design element. They can either create a dramatic effect on a building’s façade or blend in and virtually disappear. EVBs are adaptable to all building types and are ideally suited for the retrofit market or new building projects.
During a summer day, solar shading helps keep excessive heat out of the building, which can dramatically cut the need for air-conditioning. In the evening, windows are opened and the solar shading system allows the building to flush any heat build-up, again reducing the need for air-conditioning.
In winter, an intelligent EVB system remains open to let free solar energy into the building during the day, reducing energy requirements for heating. Once the sun has set, the system closes the blinds, minimizing heat loss and thus continuing to save on the energy required for heating.
EVBs allow building occupants to control the amount of natural daylight entering their spaces. They can offer significant savings in capital, operating costs, and energy. In an optimal setting, average energy reductions upward of 35 per cent annually can be realized as demonstrated by research from Germany’s Fraunhofer Institute.
A common concern expressed by architects and owners regarding the specification of EVBs in Canada relates to the shades’ use in cold winter weather. However, these assemblies have been specified in Iceland, Scandinavia, and Russia without issues. The harsh weather should not affect a durable system that has a weather sensor to know when to retract or deploy based on environmental conditions.
There are three applications where venetian systems can be used: exterior, interior, or between two panes of glass. Many types of blade options are available—perforated slats and half-perforated slats provide increased transparency (from inside-to-outside) while fully-perforated slats even allow views when blinds are fully closed. Dim-out slats have a sealing strip along the edge; it provides a black-out effect when closed and offers high stability.
The installation of an external venetian blind system is quite simple; it can be completed in a few easy steps, from assembly, to attaching it to the curtain wall. External venetian blinds can be mounted on all building types and façades, including masonry, curtain wall, or metal panels. EVBs can be specified on a project of any size, ranging from a few hundred units to several thousand. A good solar shading company can provide the design team with the proper installation details to meet the specific glazing requirements.
Dynamic solar façades
Dynamic solar facades are a monumental automated solar shading option. Similar to external venetian blinds, they are able to track the sun to maximize the control of light and heat entering the building’s interior. Unlike EVBs, however, they are non-retractable.
Dynamic solar façades are designed to let building occupants see out, so the attachment system projects off the building to allow window-washers easy access to the windows. These systems significantly reduce a building’s energy and capital equipment costs, while also preventing over- or under-shading so building occupants can always enjoy natural daylight. They can attach to all building façades (including masonry) and all types of curtain wall construction. Each attachment is engineered to meet specific wind, snow, and building loads.
Typically, blade sizes range from 150 to 600 mm (6 to 24 in.); some systems are equipped with a locking pin for easy removal. The operating blade is offered in multiple profiles, sizes, perforation options, and materials. For the final category (usually determined by desired esthetics), possibilities include:
- extruded aluminum;
- roll-formed aluminum;
- perforated aluminum;
- laminated glass; and
- wood (e.g. red cedar).
There is also expectation photovoltaic (PVs) will be incorporated in the near future.
Dynamic solar façades are attached to the building with extruded stand-offs that have no exposed fasteners. This unique attachment system incorporates three-dimensional adjustments to allow for construction tolerance on the building’s face.
Automated solar shading systems comprise high-tech climate sensors, high-efficiency motors, and intelligent controls that work in unison with its exterior blind system. The assembly is integrated into the building management system to monitor weather conditions, optimize functionality of HVAC systems, and automatically adjust the system accordingly to provide the most comfortable conditions.
The system involves interplay between sun protection products, ventilators, windows, heating, air-conditioning, and more in order to respond to weather-related influences from outside. Components include control panel with management software, a weather station (climate sensor), and controls.
Similar to an automated weather station, the intelligent controls and climate sensors use meteorological data (e.g. wind speed/direction, temperature, lighting intensity, and precipitation) to help recognize when to shift or change sunshade positions. A change in sunshade position may be necessitated for various reasons: heavy rain storm or snowfall, to reduce solar glare, or to manage the amount of natural daylight shining into the building.
A quality intelligent control system will have its software base calculations on some of the following data:
- Azimuth angles (i.e. angle between true south and the point on the horizon directly below the sun);
- sun-cut-off angles;
- shading factors;
- sun angle calculator;
- date; and
- time of day.
A full range of parameter options are available, such as:
- simple blade positioning;
- time of day controls;
- zone sensors;
- runtime values for extending and retracting; and
This sophisticated technology is easy to use and can be programmed by using an onsite computer (online), or even from a home office (offline). Control is detailed and granular, with automation overridden for manual control. The whole building’s shading system can work together holistically, or certain floors and areas can have direct management options.
Automated slat tracking
Automated control guarantees a comfortable balance between sun shading and the use of natural sunlight throughout the day/year. The slats’ angles are always in relation to the real position of the sun.
A building’s geographic location (i.e. latitude and longitude) and orientation on a site are the two most important considerations. The position and path of the sun in different geographic locations will dramatically change the shading requirements.
The slats are tracked in a maximum of seven different angles and positions. This ensures visual contact to the outside, protection against direct sun, and brings diffused light in. The intelligent control systems knows whether to close the blinds on one section of the building where there might be direct sunlight or glare, while also opening the blinds for another part of the building needing more natural daylight.
Automated solar shading is here to stay. With more and more stakeholders looking to reduce energy consumption, increase occupant comfort, and help the environment, automated solar shading is one of the few products on the market with such diverse benefits.
As many cities are implementing green retrofit policies, external automated solar shading can be an especially suitable form of retrofit. This is particularly true for schools and hospitals where calls for improved building performance are significant. Along with meeting energy-efficiency goals, the system becomes a design element, helping to make an old building look new.
1 For more on studies suggesting the positive impact of natural lighting, see The Daylight Imperative, edited by Eva Behringer. (back to top)
2 For more on this project, check out a web-exclusive case study on Construction Canada Online called“Design Allows Surrey Health Centre to Optimize Workflow.” (back to top)
Justin Joseph is a multiple-award-winning 40 Under 40 executive with years of success at establishing the vision and strategies necessary in order to position past employers as industry leaders. With a proven track record of developing and implementing solutions to quickly grow businesses within a few months by capitalizing, maximizing, and leveraging business development efforts, his firm The Boutique Agency & Consultants has worked with many clients in many industries worldwide. He can be contacted via e-mail at firstname.lastname@example.org.