Active Energy Conservation

As opposed to passive design techniques, active energy savings come from mechanical systems and appliances. Our strategies include an automated control unit, efficient mechanical equipment, LED lighting, and Energy Star appliances. Equally important are the energy-saving behaviors of the ICON Solar House inhabitants.

Controls

Home automation is a powerful tool for energy savings. Sensors in the ICON Solar House monitor conditions such as sun exposure, internal temperature, how much energy is being produced by solar systems, or how much energy the lights are using. The system is able to respond to these conditions, essentially improving livability and reducing energy consumption.

In addition to temperature and solar energy production, the ICON Solar House system monitors HVAC, A/V, security, desiccants, blinds, appliances, lights and even irrigation.

Heating, Ventilation and Air Conditioning (HVAC)

Temperatures in Minnesota can range from 100°F (38°C) in the summer, to 40°F (40°C) in the dead of winter. This means that in a Minnesota house, both the heating and the cooling systems need to be reliable and efficient. In the ICON Solar House, solar thermal energy is used to power a custom-designed latent cooling system, hydronic radiant floor heating, and energy recovery ventilator (ERV) to aid the efficiency of air circulation.

Latent cooling is the process of taking humidity out of the air. You can find an example of latent cooling in shoe stores. The white packets of silica gel draw humidity out of the air to keep your shoes fresh and dry a simple latent cooling technique. Heating Water Water is superheated by solar thermal collectors and transferred to a storage water tank. This tank contains hot water to be used for domestic needs, the desiccant dehumidifier, and the in-floor radiant heating system.  Reducing moisture makes air feel cooler in summer. Dehumidification reduces the need to run the air conditioner.  When you buy new shoes, they often come with little packets of desiccant beads to keep those shoes dry. We use the same property in the form of a liquid solution to draw moisture out of our house. The desiccant heat exchanger acts as a double-boiler, heating the solution until it releases moisture and is regenerated.  By using a liquid desiccant dehumidification system to provide latent cooling, we can improve the efficiency of the AC unit. In a typical home, the AC unit first cools the air below the dew point, which creates condensation and removes moisture from the air. This process requires a significant amount of energy, which is greatly reduced when the air contains less moisture to begin with. Our variable-speed modular dehumidification system can accommodate the changing cooling loads expected during the competition and have flexibility throughout the seasons.

In a highly insulated and tightly constructed house, a ventilation system is needed to supply fresh air. When the temperature inside is much different than the temperature outside, a lot of energy is lost just in the air that is exhausted by the fans. In general, the addition of an energy recovery ventilator (ERV) improves efficiency by transferring energy from the exhaust air to the new outside air that is being pulled into the ventilation system. This means that in winter, hot air going out helps to heat cold air coming in, so the radiant floor system does not have to work as hard.

Appliances

All of the appliances in the ICON Solar House have the highest Energy Star ratings. According to the U.S. Department of Energy, home appliances are responsible for 20% of the average energy bill.

Energy-saving Behaviors

Mechanical and design solutions can only help to a point. Small changes in our individual lifestyles can create major impacts on the amount of energy necessary. Most people know how important it is to turn the water off while brushing teeth, but what else can we do? Part of the challenge during the Solar Decathlon is to live consciously, making choices that save energy on a daily basis.
Check it out:
http://www.umn.edu/italladdsup
http://www.nrdc.org/air/energy/genergy.asp