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How the SolarWall® Technology Provides Fresh Air & Free Heat


Product description: The SolarWall® solar air heating system

The SolarWall® air heating system is a custom engineered solution containing many internal and external components. It uses solar energy to heat and ventilate indoor spaces in new and retrofit applications, as well as to heat air for manufacturing process and agricultural crop drying applications. The system design is optimized to maximize energy delivery with a minimum amount of static pressure in the airflow.

The most visible component of the system tends to be the exterior metal “solar cladding”; however a significant amount of the science behind SolarWall is in the internal framing design and component shapes.  Special vent-slit perforated collector panels are installed several inches from a south facing wall, creating an air cavity. (Southeast, southwest, east, and west wall are also possible.) The SolarWall cladding (transpired solar collector) is heated by the solar radiation from the sun, and ventilation fans create negative pressure in the air cavity, drawing in the solar heated air through the exterior panel perforations. The proprietary manufacturing equipment and design process - for both the panels and the framing system - are used to control the amount of airflow through the perforations. This maintains a consistent draw across the entire wall surface and ensures the cooler air beyond the heated boundary layer is not introduced into the air stream.

The air is generally taken off the top of the wall (since hot air rises) and that ensures that all of the solar heat produced is collected. The heated air is then ducted into the building via a connection to the HVAC intake. On a sunny day, the air entering the air handling unit will already be heated – anywhere from 30-70°F (16-38°C) for a conventional SolarWall system and 36-100°F (20-55°C) for a 2-Stage SolarWall system.  This reduces, or may even eliminate, the conventional heating load during the day.  The solar heated fresh air is then distributed into the building through the existing HVAC system or with separate air makeup fans and perforated ducting.

There are many variations to the SolarWall technology, based on a building's energy requirements or a customer's objectives. Examples include conventional single-stage SolarWall systems that can be styled, shaped and angled in a variety of colors; 2-Stage SolarWall systems for higher temperature rises; and rooftop SolarDuct® systems (these are usually 2-Stage systems to deliver higher temperature rises).

SolarWall Schematic Diagrams

As well as providing on-site renewable energy, the SolarWall® technology is also commonly specified when increased ventilation air is required, or for building remediation purposes when exterior cladding has to be replaced. In retrofit applications, SolarWall systems are one of the few technologies that can be: a) easily integrated into an existing building, and b) cost-effective in reducing a large amount of energy. A SolarWall system also acts as a rain screen.

The SolarWall technology can also make an excellent addition to a HRV (Heat Recovery Ventilator) system by preheating the incoming ventilation air and increasing the system efficiency.

Overall, decades of research and field experience ensures that whatever the design considerations may be, the SolarWall system will perform at an optimal efficiency.

Performance and Economics

  • The performance of the SolarWall technologies have been established through extensive testing and third party monitoring by organizations such as the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL), Natural Resources Canada, and numerous others in countries around the world. This independent third party verification has substantiated the energy savings that the SolarWall systems deliver.
  • The SolarWall technology provides free heat for the life of the building
  • Delivers air temperature rises of 30-100°F (16-55°C) above ambient depending on flow rate
  • Generates annual CO2 savings of 1 ton for each 5 square meters (50 square feet) of collector
  • It reduces annual heating costs by $2 - $8 per square foot ($20-$80 per square meter) of collector, depending on the type and cost of fuel displaced
  • It delivers ventilation air that can represent up to 50% of a building’s heating energy needs
  • Contributes 1.5 – 3.5 therms/ft2 (1.5 – 3.5 GJ/m2) of energy per year
  • High solar efficiency (up to 80%)
  • SolarWall systems are comparable to the cost of a brick wall, and the total installed cost after tax considerations and possible grants can mean a SolarWall system may be less expensive than other metal or masonry wall options
  • Even on cloudy days, the system provides significant energy savings as a preheating system for ventilation air
  • Lowers summer cooling costs by shading the inner wall from direct sunlight
  • Maintenance free over its 40+ year lifespan

SolarWall performance graph
 

SolarWall 2 Stage temperature with wind speeds

 


Typical SolarWall Construction

SolarWall panels on typical block wall construction    SolarWall panels on typical block wall construction

1-SolarWall panels on typical block wall construction 2-SolarWall panels on typical metal wall construction