The SP module is a packaged system which includes supply and exhaust air fans, outdoor and return air filter, and SEMCO's TEC total energy recovery wheel. The TEC wheel recovers both sensible (temperature) and latent (moisture) energy; it cools and dehumidifies the outdoor air during the cooling season while heating and humidifying the outdoor air in the heating season.

The TEC wheel utilizes a fluted aluminum substrate that is uniformly coated with a fast-acting, adsorbent desiccant. As the transfer media slowly rotates between the outdoor and exhaust airstreams, the higher temperature air gives up its sensible energy to the aluminum. This energy is then given up to the cooler air stream during the second half of the revolution. Just as the temperature is captured and released, so is the moisture. The wheel’s desiccant coating has an enormous internal surface area and a strong attraction for water vapor. Since the opposing airstreams have different temperature and moisture contents, their vapor pressures differ. This difference causes the transfer of latent energy.