Thermal insulation of doors and windows

At present, "thermal insulation effect of door and window products" is no longer just a general adjective. If consumers care about the thermal insulation capacity and K value of doors and windows (heat transfer coefficient of doors and windows), they can already buy door and window products of different thermal insulation levels just as they can buy televisions by resolution.

So if you want to go to the store and buy doors and windows with better thermal insulation performance (in fact, thermal insulation=thermal insulation+cold insulation), don't directly ask "What aluminum alloy doors and windows with better thermal insulation performance?" This is not professional enough, and you will only get the mechanical answer of "rest assured, big brother! Our brand has the best thermal insulation".

You should ask the shopping guide:

Do you have a performance inspection report for doors and windows? What is the thermal insulation performance of XX series? Oh, this series has good thermal insulation performance? Tell me which structures improve thermal insulation.

01 Performance inspection report and K value of doors and windows

The performance inspection report of doors and windows, that is, many domestic door and window brands will send their various product series for inspection, and the specific performance parameters of doors and windows, such as air tightness, sound insulation, thermal insulation, etc., will be obtained by the professional inspection unit.

Heat transfer coefficient of doors and windows, namely, K value. The main index used to measure the thermal insulation performance of doors and windows refers to the heat transferred through 1 square meter area within 1 hour under stable heat transfer conditions with the air temperature difference of 1 degree (K, ℃) on both sides of the enclosure. In general, the lower the "K value" (pictured above), the slower the heat in summer and the slower the cold in winter, the better the thermal insulation performance of doors and windows; The higher the "K value", the worse the thermal insulation performance.

Check the K value in the door and window performance inspection report, which is the fastest way for consumers to get the heat insulation performance of the product.

With the popularity of system doors and windows in recent years, there are more or less manufacturers or businesses (usually with large brands) in every city that adhere to the principle of "speaking with data".

It is relatively simple to choose and buy from such businesses. Buy according to the thermal insulation level (higher requirements for adding glass), and then focus on investigating the installation capacity and bargaining of the businesses.


Of course, at present, most door and window brands and businesses do not have such test reports. At this time, we should learn and observe the following knowledge:

02 Thermal insulation elements of doors and windows

1. The larger the series, the more thermal insulation, the wider the insulation strip

Many businesses have no brains to sell. If you want to heat insulation, you should choose high series doors and windows. In short, the larger the series is, the wider the windows are!

no The motivation of the business here is not pure, and the concept is changed!

The larger the series is, the more thermal insulation is relative. Only the wider the thermal insulation strip is, the more thermal insulation is absolute (only compare profiles)! This is also the origin of the word "bridge breaking" in aluminum doors and windows. The thermal insulation strip is like a cold bridge, which blocks the heat transfer between the two profile hot bridges:

In the overall K value of doors and windows, the influence of frame and sash (i.e. aluminum profile) accounts for 20% - 30%. The best way to improve its thermal insulation capacity is through the width of thermal insulation strip:

2. Insulating glass is the main force of insulating glass, with a Low-e higher level:

Glass accounts for 70% - 80% of the whole window area, so the thermal insulation of the glass part plays a decisive role in the impact on the thermal insulation performance of the whole window (the data is 62% - 74% of the whole window).

Generally, we choose the glass with better thermal insulation performance from the four glass types of insulating glass, three-glass and two-chamber, Low-e insulating glass, and Low-e three-glass and two-chamber (the unusual ones are vacuum glass and laminated composite glass used for protection or sound insulation).

3. Wall thickness has no effect on thermal insulation of bridge-cut aluminum

Like "the bigger the series, the more heat insulation", some businesses also equate the wall thickness with the heat insulation paint. Pengge has seen a group of experimental reports on bridge-cut aluminum. The wall thickness and series have an impact on the wind pressure resistance of doors and windows, but have little impact on the thermal insulation performance (K value fluctuates around 0.01).

4. The sealing structure is exquisite: three seals, isotherm, and the rubber strip keeps opening

Whether the thermal insulation performance of the door and window structure is good or not depends on the thermal insulation strip and its sealing structure. How to look, there are three points: whether there are three seals; Whether there is isotherm; Whether it is a press-in adhesive strip.

The following is a comparison between two seals and three seals ▽:

The three-way sealing structure is to add a sealant strip on the frame and fan profiles (△ see the "middle seal" on the right side of the figure above), so as to separate the water and steam mixing cavities of the two seals (▽ cavity schematic diagram), forming the water-tight cavity on the outdoor side and the air-tight cavity on the indoor side, which improves the air seal, thus enhancing the thermal insulation performance.

During the exchange of cold and hot air inside and outside the doors and windows, the two broken bridges are in the same line, which is more conducive to forming an effective "cold and hot bridge barrier". There is less cold and hot air running around, reducing unnecessary heat loss.

The following is the comparison diagram of whether it is press-in adhesive tape ▽:

You can try to ask the door and window owner whether your window adhesive strips are worn in or pressed in. It can also be observed on the sample angle that the notch of the penetrating rubber strip is longer and shallower than that of the pressing rubber strip; It can also be observed from the finished window to see whether the adhesive strips at the corners of the window are cut off, or whether there are traces of glue adhesion.

The press-in adhesive strip can be "seamless" connected at the corners of the window (when turning) without violence, which improves the air seal and thermal insulation performance.

5. Cavity filled with thermal insulation material

Thermal insulation materials can also improve the overall thermal insulation performance of doors and windows:

The principle is to fill the cavity between the glass and the profile, and the cavity between the heat insulation strips with thermal insulation materials to reduce the heat and cold exchange rate between the cavities.

03 Which are not the thermal insulation elements of doors and windows

By studying the heat insulation elements of doors and windows listed above, I believe you have some confidence in selecting "doors and windows with good heat insulation performance". Here are some non-door and window thermal insulation elements listed by Musuo, so as to make sure that the business is properly settled:

1. Brand: Mobile phone buyers have a scale in their mind: "select Xiaomi for price performance, select Huawei for photos, and select Apple for simple operation". The door and window brands have no reference meaning for the positioning of products, just take the parameters and structure.

2. The series and wall thickness mentioned above: the reason is not repeated.

3. Laminated glass and its composite glass: The laminated glass for home decoration doors and windows is mostly used in the sunlight roof and soundproof scene. Its advantages are safety and soundproof ability. It is not as practical to use the laminated insulating glass to insulate as the upper three glasses and two cavities.

4. Window type: window type is not positively related to heat insulation performance, but sealing performance. The merchant said that it is not absolute to open the inside and reverse the heat insulation, open the outside and push the sliding window. It is the king's way to select the heat insulation elements provided by Pengge.

04 Other related to thermal insulation performance of doors and windows

If you want to achieve more perfect thermal insulation of doors and windows, you can also learn three points:

1. Sealing and heat insulation of installation

The foaming agent in the installation gap of doors and windows is full, and the sealing and durability of the external wall sealant will certainly affect the performance of the thermal insulation of doors and windows. It is necessary to inform the installation workers in advance not to omit and supervise the work on site.

Some windows and doors will be installed with aluminum alloy auxiliary materials such as splicing, splicing, splicing, corner, etc. It is better to ensure that these materials are "bridge broken".

This is very important, and it is easy for consumers to ignore it. If the installation auxiliary material used is non-broken bridge, then its joint is a thermal insulation bug, from which the continuous heat will be transferred, greatly reducing the exertion of the thermal insulation of doors and windows.

2. Sunshade material

The shading materials for doors and windows are divided into internal shading and external shading. Now, with the improvement of building energy efficiency standards, more and more developers have been equipped with shading products for use. Those with higher requirements for the living environment can also be considered

Outdoor retractable sunshade, arm-type sunshade, indoor built-in blind insulating glass, sunshade, honeycomb curtain, etc. can be considered, and outdoor is the best priority (the shading effect is definitely not as good as outdoor when the light enters the room).

3. Thermal insulation scheme of sunlight room:

There are two practical and feasible thermal insulation schemes for solar rooms, namely, "Decao solar room shading scheme" and "floor heating solar room thermal insulation scheme".