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[Energy] #5 A passive house saves energy by itself

by Eco Generation | 10-04-2020 14:27 Comments 4 Comments recommendations 0 recommendations

A passive house saves energy by itself



By Science Columnist Ho-Gwan Ko



In cold winters, there is nothing like watching enjoyable movies with hot chocolate in a warm house. On hot summer days, it is nice to fiddle around at home with the air conditioner on; taking even one step outside your house could be a challenge.

However, it takes energy to keep your house in a pleasant condition. In winter, homes are heated with gas or oil, and electricity is used to cool the air in summer. As a result, carbon dioxide is released into the atmosphere, worsening climate change. If extreme weather occurs, more heating and cooling is needed, creating a vicious cycle where more carbon dioxide is emitted.

The concept of a passive house is to reduce the energy used for heating and cooling the building. The house keeps the room temperature properly with minimal heating and cooling. The concept was first created in 1988 by German physicist Wolfgang Feist and Swedish engineer Bo Adamson.


Passive House

▲ The first Passive House in Darmstadt, Germany (Photo credits to: Peter Cook)

A passive house utilizes as much external energy, including sunlight, as possible for heating in winter. It also prevents heat emitted from electronics, gas stoves, and the human body inside the building from escaping to the outside. If it is still not warm enough, the conventional floor heating system supplements heating requirements.

To attract a lot of sunlight, a building needs to face the south. While a large window in the south can bring in a lot of sunlight, this can also let heat escape through it at night. Therefore, the size of a window should be adequate, and it should provide excellent thermal insulation. Usually, passive houses have triple glazed windows. In addition, a thin layer of metal-like material is applied to the glass surface to block heat. This will help not lose heat in winter and keep outside heat from entering in summer.

The insulation of not only windows but also the entire building is important. For walls, enough insulation is necessary to protect heat from leaking out. In addition, the entire building should be sealed to keep warm air from escaping. To save energy, good design has to be compromised; although it may seem boring, the building needs to be simply rectangular in order to minimize the area of the walls that the outside air contacts. Unfortunately, even a pretty roof is not recommended, as it is not good for insulation and airtightness.

Although preventing air flow from and to inside and outside a house helps conserve heat, it causes indoor air quality issues. Therefore, a passive house is mechanically ventilated to draw fresh air from outside using a heat recovery ventilator.

This device transfers heat from one side to the other, exchanging indoor and outdoor air. Fresh, cool outdoor air enters the home through this device. Meanwhile, warm and poor-quality indoor air flows out of the house. At this point, the two airs cross each other, with the heat of the warm air being transferred to the cold air. Eventually, the fresh, cool air from the outside becomes fresh, warm air and enters the house. The polluted and warm inside air becomes cooler and goes out of the house.

However, if the house is too airtight for the purpose of preventing heat loss, it would be too hot in summer. There are many things to consider when building a passive house to prevent the indoor temperature from going up in summer. First, it is important to prevent heat from entering the house. Painting the exterior walls bright is one way. This is why houses in the sunny Mediterranean are painted white. Reflecting a lot of sunlight, the walls get less heat.

In summer, as opposed to winter, the light coming from windows should be minimized. As mentioned earlier, the coating on the glass blocks external heat. In addition to this, blinds or shutters need to be installed outside the window to block sunlight. This is more effective for blocking sunlight from entering the house than blinds installed inside. Eaves and awnings can also be used to cover the light. If installed at the right length, they can block the light in summer when the sun is higher and let it come into the house in winter when the sun is lower. In addition, you can keep cool air longer by flowing cold water into the pipes used for floor heating.

Passive houses are not yet widespread. It costs more to build them compared to ordinary houses, and the concept, which was invented in Europe, may not fit well with the climate in other countries. However, there will be other alternatives to develop and distribute energy-saving houses suitable for each country.



  • PALLAVI SHORI says :
    What an interesting topic it is, good work.
    Posted 15-09-2020 18:19

Mandip Devkota

  • Mandip Devkota says :
    Greetings Eco Generation
    I hope all are doing well
    Thanks for this wonderful and informative report
    Posted 15-08-2020 14:25

Asmita Gaire

  • Asmita Gaire says :
    Greetings Eco Generation
    I hope you are doing well.
    before reading the report I was like , what a passive house?
    After I read it, I am genuinely thankful towards you Tunza for this series.
    Thank you so much for this report.
    Green cheers
    Asmita Gaire
    Posted 08-05-2020 15:50

Kushal Naharki

  • Kushal Naharki says :
    Thanks for the next article of the series. This is very interesting and informative
    Posted 10-04-2020 14:51

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