What is a Passive Loss?

Passive energy-saving houses (German: Passivhaus ^[1] ) can be translated into passive houses, which are energy-efficient buildings based on passive design. Passive houses can adjust the room to the right temperature with very little energy consumption, which is very environmentally friendly.

Passive house

1 Passive houses are not only suitable for dwellings, but also for office buildings, schools, kindergartens, supermarkets, etc.

The concept of passive houses originated in Sweden

Passive house envelope structure

The insulation layer is particularly thick. As shown below:

The yellow part is the insulation layer, the left side is the insulation layer thickness of the general house, and the right side is the insulation layer thickness of the passive house.

Sample of clay bricks with internal cavity filled with insulation

Construction site with extra thick foam insulation board

Schematic illustration of the three-dimensional section of the passive house wall and window structure

Passive house super energy-saving windows

"Passive houses" not only reduce heat loss, but also increase insulation and comfort. Even in cold and frosty weather, the indoor glass can exceed 17 ° C.

Indicators of passive residential windows:

A, Uw value0.8W / (m & sup2; K)

B, Ug-1.6 W / (m & sup2; K) · g <0, the value of g is generally around 0.5. This condition is met,

It is shown that the solar thermal energy obtained by passive windows in winter is greater than the energy lost due to conduction.

Three-dimensional cut-away schematic diagram of three-layer glass thermal insulation window

Passive houses have extremely high performance requirements for windows. At present, very few window companies in China can produce such windows. However, it is gratifying that in 2012, domestic window companies have already approached the Passivhaus-Institut mentioned earlier to discuss and cooperate on a series of issues such as the energy efficiency of building exterior windows. And has developed a product that meets the standards of passive house windows-Mori Eagle PASSIVE120. The window frame uses a super heat-insulating composite frame, and the glass uses a three-glass two-cavity structure (double LOW-E, double warm edges, and argon-filled), which makes it have super strong thermal insulation performance. Can meet the "passive house" insulation requirements.

Passive house building structure without heat bridge

Some parts of the building envelope structure, due to the temperature difference between indoor and outdoor, form areas with relatively dense heat flow and low internal surface temperature. These parts become bridges with more heat transfer, so they are called thermal bridges, and sometimes they are also called cold bridges.

The so-called thermal bridge effect, that is, the physical effect of heat conduction, is due to the presence of concrete ring beams and structural columns at the floors and corners, and concrete materials have better thermal conductivity than wall materials At the same time, due to poor indoor ventilation, large temperature differences between indoor and outdoor during late autumn and early winter, frequent contact between hot and cold air, uneven thermal conductivity of the wall insulation layer, resulting in thermal bridge effect, causing condensation and mold on the interior wall of the house Even dripping.

The structure of a thermal bridge in a passive house can avoid the above phenomenon.

Good sealing of passive houses

In the detection of positive and negative pressure, there are strict requirements for gas loss. Because if the seal is not good, hot and cold gas convection will occur, resulting in heat loss.

Passive house ventilation system

Active ventilation (counter-current air / air heat exchange) provides high-quality air, and at least 75% of the exhaust heat is used to heat the incoming fresh air. At this time, the exhaust air and fresh air are not mixed. Because the passive house is sealed very well, the air change can be optimized and strictly controlled at 0.4 / h (air exchange rate per hour).

The fresh outdoor cold air first enters the core control component of the indoor energy recovery and ventilation system through the green pipe line. The indoor room contains a certain amount of heat, and the yellow control line also collects the core control component of the indoor energy recovery and ventilation system. Energy recovery ventilation system keeps most of the heat in the exhaust gas and heats the fresh air entering the room. The pre-heated fresh air is sent to each room through the blue pipe line. The exhaust gas after heat recovery is discharged to the outside through the pipeline.

Indoor energy recovery ventilation system, solar hot water system + boiler hot water system + floor heating system + radiator heating + domestic hot water-hot water exchange storage hybrid system, schematic diagram.