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.
There are many variations to the SolarWall technology, based on a building's energy requirements or a customer's objectives. The most visible component of the system tends to be the exterior metal cladding; however a significant amount of the science behind SolarWall is in the internal framing design and component shapes.
Specially 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.) SolarWall systems may also include some exterior glazing for higher temperature rises. The metal 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 panel perforations. The proprietary manufacturing equipment and design process - for both the panel 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. Since the air entering into the air handler has already been preheated – anywhere from 30-70F (16-38C) on a sunny day, and less on a cloudy day – this solar heating reduces the energy load on the conventional heater. The heated fresh air is then distributed into the building through the existing HVAC system or with separate air makeup fans and perforated ducting.
Interior Fan
Rooftop HVAC Unit
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 improvement to a HRV (Heat Recovery Ventilator) system by preheating the incoming ventilation air and increasing its 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 technology has 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 technology delivers.
- The SolarWall technology provides free heat for the life of the building
- It reduces annual heating costs by $3 - $10 per square foot 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 needs, and contributes 1.5 – 3.5 therms/ft2 (1.5 – 3.5 GJ/m2) of energy per year
- It has an operating efficiency of up to 75% (rated by both the Canadian and US governments)
- On a sunny day, the temperature in the SolarWall can raise the air temperature by 30 F to 76 F (16 C to 40 C) depending on flow rate
- The SolarWall technology delivers annual CO2 savings of 1 ton for each 5 square meters of collector
- 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
Typical SolarWall Construction
1-SolarWall panels on typical block wall construction 2-SolarWall panels on typical metal wall construction
Summer Cooling
SolarWall® provides summer cooling by preventing solar radiation from striking the south wall of a building. Warm air between the solar paneling and the building rises and is ventilated through holes at the top of the cladding. This reduces cooling loads in the building. Fresh ventilation air is drawn directly into the building by way of by-pass dampers.
RainScreen
The SolarWall® system acts as a rainscreen for the building wall it covers.
Indoor Air Quality
Installing a Solarwall system allows companies and businesses to meet ventilation standards required by code, without spending a prohibitive amount on an ongoing basis to heat that air. Good indoor air quality is the result of an adequate, continuous, supply of fresh outdoor air. ASHRAE (the American Society of Heating, Refrigeration and Air Conditioning Engineers) states that the best way to avoid illness due to poor indoor air quality is to increase the volume of fresh air entering a building. The negative impact of uncontrolled entry of outdoor air is increased heating costs. SolarWall solar energy systems can solve this problem by using solar energy to preheat ventilation air.
Maintenance
SolarWall systems are building integrated, contain no moving parts, and are virtually maintenance free. Installing a system over a masonry wall also protects the wall from rain and moisture, which can cause bricks to crumble.