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Passive cooling: survive the hot months in an environmentally friendly manner
Passive cooling: survive the hot months in an environmentally friendly manner

Video: Passive cooling: survive the hot months in an environmentally friendly manner

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Video: Passive Cooling Techniques are Meaningless | Sustainable Architecture 2023, January
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Temperatures are climbing higher and higher worldwide, and a new heat record is set every summer. In order to get through the hottest months, the topic of building cooling is becoming increasingly important. But of course we want to be as energy-efficient as possible in order not to heat global warming even more - that is, through so-called passive cooling. They keep the building's rooms at a comfortable temperature without air conditioning. You can find out exactly how passive cooling works here.

Table of contents Table of contents passive cooling: tempered room air without air conditioning

  • Passive cooling: think about summer when building
  • Passive cooling system: heat pump
  • What does a heat pump cost?
  • Passive cooling options

Table of contents Table of contents passive cooling: tempered room air without air conditioning

  • Passive cooling: think about summer when building
  • Passive cooling system: heat pump
  • What does a heat pump cost?
  • Passive cooling options

Anyone who has been lying sweaty in bed at night and despite all the home remedies against the incredible heat has no eye knows the need for air conditioning only too well. The desire to be able to achieve great things with a little finger movement on the remote control and finally be able to sleep through the night again is understandable. Who wants to stagger through life as a zombie between early July and late August? But exactly the supposedly redeeming button press actually contributes to the exacerbation of the problem through the immense power consumption and the functioning of the air conditioning system and causes it to get even hotter the following summer. Then press the little button even more and in three years you won't be able to get through the day without air conditioning. A vicious circle.

Passive cooling: think about summer when building

Passive cooling creates environmentally friendly relief. And that starts with building a house: Avoid facing south of your house. Or, if there is no other way, at least put the bedrooms on the north side, not on the south side. Solid walls and ceilings are preferable to lightweight construction because they can keep the heat out of the building for longer. Isolate the building consistently and carefully. Wood fiber boards and cellulose insulation materials have proven to be good heat protection in summer.

Floor-to-ceiling windows contribute to beautiful living - but be sure to have roller shutters or blinds in combination with awnings from the outside in order to provide shade in summer. And have the window panes covered with special sun protection film. Plant house trees in your garden at strategically favorable points - the larger they become, the more shade they provide. A green roof can also help fight the temperatures. A combination of several passive cooling options would of course be the best solution. And: When it comes to heating, think about cooling. For example with a heat pump.

Jalousien am Fenster
Jalousien am Fenster

Floor-to-ceiling windows provide a pleasant light in the living area, but in summer also an unbearable heat in your own four walls.

Photo: iStock / UJ Alexander

Passive cooling system: heat pump

The fact that the heat pump can also be used to cool the house in summer is an unimagined possibility of use for one or the other - the name of the heat pump alone suggests that its main task is pumping and transporting the heat. But: Where there is warmth for winter, there is also cool air for summer. Namely under the earth.

A heat pump, in combination with the distribution system suitable for your home, is one of the slower, but still one of the most effective passive cooling systems. It can lower the room temperature by up to five degrees Celsius. However, the cooling capacity gets a little weaker every day, so the passive cooling capacity of your home is consistently reduced over the summer. This in turn benefits you in autumn and winter, because depending on the nature of the floor, you have a bubble with warm air from which your heat pump can draw more warm air for heating.

The water from the ground-coupled heat pump system is fed through a so-called plate heat exchanger through the soil under your house or through the groundwater and thus cooled. From a depth of around 15 meters, the earth's temperature is a cool ten degrees Celsius - all year round without human intervention. However, the heat emitted accumulates in the ground or in the groundwater, so that slightly warmer air or slightly warmer groundwater is available the next time it is run. The longer the heat pump is in operation, the warmer the soil and the groundwater become and the lower the temperature difference between the water flowing through and the environment that the water is supposed to cool down.

The compressor of the heat pump is not switched on in the cooling action described, only the circulation pump works. Therefore, this variant falls under the energy-saving, passive cooling, which produces almost no CO2. You can also actively cool your house with a heat pump. The heat pump works as a cooling unit, almost like a refrigerator, and becomes a so-called reversible heat pump. A less energy-saving cooling option, which still has a power saving potential of 20 percent compared to conventional air conditioning, is said by experts. A combination of the two techniques is also possible.

Luftwärmepumpe
Luftwärmepumpe

The cost of an air source heat pump depends on the size of your property and the necessary accessories.

Photo: iStock / KangeStudio

What does a heat pump cost?

Depending on the type and model, the purchase of a geothermal heat pump, air source heat pump or groundwater heat pump for an average single-family house costs between 4, 000 and 12, 000 euros. In addition there are the costs for the development and the accessories (between 500 and 8, 000 euros). However, the price also depends on the type of heat pump. While an air heat pump has to be set up at a sufficient distance from the neighbor and your own bedroom window due to the somewhat loud operating mode, but does not have to be buried deep into the ground, a borehole of up to 100 meters is necessary for a geothermal heat pump with probes.

You need to have two wells drilled for a groundwater heat pump. The initially high costs are amortized because the heat pumps consume electricity for 500 to 1, 000 euros annually, depending on the provider and the individual price, of course. A heat pump buffer storage must be added for a one-off payment of 500 to 2, 000 euros as well as other maintenance and repair costs of up to 200 euros per year. So you are right to state that the installation of a heat pump, including the retrofit, is expensive. However, it can be subsidized on the one hand and on the other hand you kill three birds with one stone: they heat and cool - and that saves energy and is environmentally friendly. A clear conscience and cool rooms, what more do you need in a hot summer?

Passive cooling options

But in the fight against unbearably hot bedrooms, there are more passive cooling options than just the heat pump:

  • Evaporative cooling works in a similar way to the shower used to cool down in summer: the water evaporates on a heated body and releases cold in the process. The hot air is passed through or over a so-called moist environment, for example a surface kept moist. The moisture evaporates and the cool air is distributed in the house using air ducts. Evaporative cooling is generally considered to be very powerful, economically and ecologically sensible and, unlike air conditioning, cannot fail in extremely hot weather - however, it requires water to function and also takes a while to generate the first cool air flows. Because vaporizing is a very slow procedure.
  • The earth air well is not a new invention, but a passive cooling of the house, which the Romans are said to have used. Similar to the heat pump, it uses the natural cold of the earth and then distributes it around the house. The earth air well requires a passive ventilation system for this. The highlight of this passive cooling: In autumn you can use the natural air well to preheat the rooms. Because the fresh air is introduced underground via a pipe into the house and then distributed from there: pleasantly cool air in summer, slightly warmer in winter. The air that this passive cooling system distributes in your building is also filtered through gravel, sand and earth and is therefore almost free of ozone and pollen. The humidity is also better regulated by this three filter. However, before you build an air well, you should find out about the radon concentration in the earth in your area.
  • Latent heat stores adopt the state of matter of the material from which they are made: When the temperature rises, the so-called phase change material, such as salt hydrates or paraffins, binds the heat continuously and for several months; when the temperature falls, however, there is heat and warms the rooms. The best known latent heat stores are probably the small, reusable hand warmers that fit in every pocket. In buildings, this passive type of cooling works particularly well in combination with plasterboard and plaster. A solar system is often installed for latent heat storage

Sabrina Deckert

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