Solar Energy Harvesting Systems

Commercial Systems

MatrixAir® Solar Air Heating

By Brian Wilkinson, Matrix Energy Inc, Quebec, Canada

Product Description

Brief Concept Description

Brief concept description While resembling conventional exterior metal facades, unglazed transpired solar collectors (TSC) use a buildings HVAC system to create negative air pressure used to pull air inside the building through a finely perforated, sunfacing metal absorber. TSCs are cost-effective, efficient, simple, aesthetically pleasing systems that require virtually no maintenance over their estimated 40-year useful life.

Figure 10. Close up of MatrixAir® absorber.

Architectural and Technological Integration into the Envelope

Architectural and technological integration into the envelope MatrixAir® TR systems are specifically designed for harmonious building integration with a buildings’ façade, blending seamlessly with its overall look and appearance. Systems may be as conspicuous or as inconspicuous as the building owner desires, since the exterior perforated absorber may be made using a variety of exterior profiles and dark colours and then site-installed in any orientation. Weighing 1-1.5 kg/m2 of collector area, such systems are attached to the new or existing buildings’ structure with a combination of vertical and horizontal framing components designed specific to each project. They also serve to create the air cavity in which the preheated air is collected and directed to the fresh air inlets. No special tools nor training is required of the exterior metal cladding contractors engaged to install such systems in accordance with the engineered MatrixAir® installation drawings provided for each system.

Integration into the Building: System and Comfort

Integration into the building: system and comfort In addition to its ease of architectural integration, transpired solar collectors work seamlessly with the buildings’ heating, ventilation and control systems. Preheated air is ducted to the buildings’ centralized HVAC system via equally spaced air outlets from the collector or via a top mounted plenum running across the top of the collector for distribution within the building. Motorized wall or roof mounted bypass louvers are activated for summer seasonal operation or when preheated air is not required.

Performance is susceptible to elevated ambient wind, thus unit air flow is an important design criterion. Façademounted, metal transpired solar collectors provide optimum return on investment when operated at flow rates of 75 to 165 m3/h per m2 of collector area; the higher unit air flows particularly suited to tall buildings such as multiresidential condominiums.These are not stand-alone systems: while TSC’s will cost effectively contribute 20% and up to 40% of the energy required for ventilation air heating providing a temperature rise of up to 25 °C over ambient temperatures, these systems will require an auxiliary heating source in most installations to ensure comfort of the building occupants.

On average, MatrixAir® systems typically yield 420 to 550 kWh/yr per m2 of collector area. Prefeasibility studies and energy savings estimates of the MatrixAir® solar air heating system may be made using RETScreen® software developed by Natural Resources Canada.

Figure 11. Installation on IKEA, Retail building.

Figure 12. Installation on an emergency services and training facility, Municipal building.

Figure 13. Installation on Light Armoured Vehicle Maintenance Facility, Military building.

Figure 14. Installation on Schluter Systems office building, Industrial building.

Figure 15. Installation on Quebec Animal Pathology Laboratory, Institutional building.

SWOT Analysis

Strengths

The system is aesthetically versatile, with a simple design and several possibilities for customization
It is a highly effective, low-cost and low-tech solution
The system can be easily installed and integrated with the mechanical ventilation system
Air filtration is induced by static electricity across the perforations
The system is durable and has zero maintenance requirement as there are no moving parts other than the HVAC system to which it is connected
It is comprised of recycled materials and can be easily recycled at end of use
There is an extensive history of proven performance across a wide variety of applications

Weaknesses

It requires auxiliary or supplemental heating system
It requires south facing facades with negligible shading
No thermal storage is available at this time to cope with time shifts between solar radiation and heating demand
The colour choice is limited, as optimum system performance is coincident with dark absorber colours.
Marginal operating costs are added to the HVAC system at higher flow rates due to higher operating static pressures
It requires a proper design, installation and HVAC integration for best performance

Opportunity

It is applicable to all buildings in the commercial, industrial, institutional and multiresidential markets in cold climates
It is applicable to new or existing buildings
Solar air heating may be integrated with other heating technologies such as heat recovery, geothermal and photovoltaics

Threats

Ventilation integrating heat recovery is a competing technology
The simplicity of design leads to naïve, inexperienced competition
Low awareness about solar air heating might hinder the success of this kind of solutions

Lessons Learned

Transpired solar collectors (TSC) are a deceptively simple, effective, highly efficient and long-life solution for fresh air heating. However, their optimum performance is only gained via sourcing through experienced, TSC manufacturers offering independently certified products.
Awareness of building integrated TSCs and their design for optimum performance amongst building professionals building owners remains low.
The integration of TSCs with mechanical systems and the building’s architecture is uncomplicated and straightforward when addressed during the initial stages of building design or renovation.
The incremental cost of the TSC systems should only be used to gauge their simple return on investment.
In new construction in particular, careful attention to the type and installation of the membrane used to separate the insulation from the preheated air cavity is required.
While TSCs require no maintenance, and their perforated absorbers may be installed in any orientation, practice has shown that horizontal profiles do tend to accumulate more dirt and dust, than do vertical or diagonally installed absorbers, which may therefore impede their energy output.
As ambient wind has considerable impact on their performance, TSCs installed in windy locations, or those installed on taller buildings should be designed at higher unit air flows per collector area for maximum cost efficiency.

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