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Passive & Active Cooling

Naturally air condition your home with passive cooling

In a house designed for passive cooling, your home interiors are kept naturally fresh, cool, and comfortable on hot summer days, but with little to no energy use. Passive cooling is a home design strategy that works by removing heat from a home through natural ventilation, and also preventing heat from entering the home in the first place through heat-gain prevention. This approach is called “passive” because it can require no special technological or mechanical devices, just smart design and quality home construction.

Natural ventilation is achieved through three strategies: cross ventilation, convection through stack effect, and Venturi effect. By utilizing a combination of these different passive strategies, a home can be cooled on both breezy and non-breezy days. In order to set up these effects within a home, windows are positioned low to the floor on the cool side of the building and high windows are positioned on the high-wall side of the building. Stack effect, for example, helps to cool the home on a non-breezy day. In this strategy, a natural vacuum is generated throughout the home when hot air rises and exhausts through the high windows and fresh, cool air enters through the low windows. The air pressure differences due to hot and cold variations inside the building and outside the home create a natural cross breeze. This air movement encourages evaporation of moisture on our skin and gives the sense of cooling. AKA, free air conditioning! Prevailing wind directions are also taken into effect to further pressurize the home, promoting a jet-like Venturi effect, which increases air flow rate within the home.

A high-performance building envelope is the second component in passive cooling design and is used to prevent interior heat gain during the hotter months. This is done by constructing walls, roofs, and floors that are very well-sealed and insulated. A high-performance building envelope not only prevents summer heat from entering the home, but also prevents heat loss in the colder months. This helps promote energy-efficiency within the building during all seasons.

To learn more check out our article, Passive Cooling Design: The Natural Way to Air Condition Your Home, that was published in Distinctly Montana.

Energy-efficient active cooling

Varying degrees of mechanical systems can be integrated with passive cooling strategies to enhance the effects. These systems are “active” because they require added energy sources, however, energy-efficient apparatuses can be utilized or the electrical demands of active cooling systems can be offset by solar photovoltaic panels in conjunction to inverters which turn 12v into 110v. The simplest active cooling examples are portable fans or ceiling fans, which mechanically move air to help set up air circulation.

At the Hawk Ridge Home, the back-up radiant floor heating system is run by an efficient air-to-water heat pump, which is turn, is powered through solar electricity. In the summertime, the air-to-water heat pump can be programmed operate similarly as an air conditioner to efficiently cool the radiant concrete slab floor. Just as the floor mass can be used to store heat, it can also be used to store cold.

Modern Solar Home Video

Passive cooling and passive solar design go hand in hand and share many multi-functional purposes year round. Watch our video to learn more about passive and active cooling strategies in a modern solar home. We also discuss hows active solar (PV) can be used to provide electricity for running an air-to-water heat pump to heat and cool the radiant floors.