3.1 the passive room with good thermal insulation system needs to minimize the cold and heat loss of the building, control the temperature difference between the inner surface of the enclosure and the indoor temperature not to exceed 3 ℃, and the heating energy consumption demand not to exceed 15kw · H / m per year.

Therefore, the passive room strives to improve the air tightness of the enclosure system and achieve “all-round package”.

It is a self-supporting residential project.

The thermal conductivity of other thermal insulation materials is about 0.03W / (m · K), except that the thermal conductivity of vacuum thermal insulation plate can reach below 0.01W / (m · K).

Especially in Beijing, where the project is located, the integration of structure, thermal insulation and decoration has been vigorously promoted.

Most of the tie pieces are metal materials with high strength, and the heat transfer coefficient is much greater than that of the thermal insulation material, which is easy to form a cold bridge.

1.2 precast buildings combining thermal insulation and decoration advocate the use of precast sandwich panels composed of inner leaf panels, sandwich insulation and outer leaf panels to achieve the integration of structure, thermal insulation and decoration.

The proportion of precast buildings above the ground is 100%, the prefabrication rate is not less than 65%, and the proportion of full decoration is 100%.

According to the standard atlas passive low energy consumption buildings – residential buildings in severe cold and cold regions (16j908-8), in order to ensure energy consumption and comfort, passive buildings in cold regions need to meet the heat transfer coefficient of external walls and roofs ≤ 0.15w / (m · K); Heat transfer coefficient of ground and basement exterior wall ≤ 0.18w / (m · K); Heat transfer coefficient of external doors and windows ≤ 1.00w / (m · K).

Therefore, the realization of the facade effect becomes the difficulty of the construction drawing design (Fig.

In this project, there are buildings with north-south direction and east-west direction at the same time.

3).

1 and 2).

3.1.1 external wall (1) in the selection of external wall insulation materials, the project considers hard polyurethane, extruded polystyrene board, graphite polystyrene board and new materials – vacuum insulation board.

1.1 treatment of component gaps.

Except for the commercial and supporting functions of A4 # and A5 # ground floors, the rest of the above ground parts are designed according to the requirements of passive ultra-low energy consumption buildings.

2 basic information of Haidian Yongfeng Industrial Park project 2.1 project overview Haidian Yongfeng Industrial Park project is located in the Yongfeng Industrial Base outside the North Fifth Ring Road of Haidian District, Beijing.

2.2 technical difficulties in this project, the construction drawing design is carried out for the above three precast passive residential buildings.

The coarser or denser tie pieces aggravate the formation of cold bridges, making it difficult to promote the peripheral protection system integrating structure, insulation and decoration in passive buildings.

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However, the insulation layer thickness of passive buildings in cold areas is larger than that of ordinary buildings, which can reach more than 200mm, which greatly increases the strength requirements of tie pieces.

The passive room strives to maximize the use of natural heat, reduce the loss of heat and cold caused by insufficient insulation or airtightness, and achieve low energy consumption.

A good thermal insulation system can significantly reduce the heat exchange of buildings, control the heating and cooling energy consumption of houses, make the indoor temperature uniform, reduce the cold and heat radiation, improve the comfort of houses, and avoid dew condensation in winter.

good insulation system, complete air tightness, no cold and hot bridge design, passive door and window system and fresh air system.

The gap treatment between precast components has become one of the difficulties in the design of precast passive buildings.

According to the above design principles, the specific solutions of the project are as follows.

There is a contradiction between the two.

It is necessary to study the impact of different orientations on the design of passive houses in the design stage, and collect all the parameters and indicators of each individual as comprehensively as possible through real-time monitoring of the operation nodes.

Rebar Support Chair

The main difficulties include: (1) both the precast technology and the passive ultra-low energy consumption technology have high design difficulties.

1 difficulties in the combination of passive ultra-low energy consumption technology and precast buildings of China building standards design and Research Institute Co., Ltd.

Figure 1 passive house and courtyard Figure 2 Schematic diagram of passive house location of Haidian Yongfeng Industrial Park project 3 rich facade effect 3 passive technology application of Haidian Yongfeng Industrial Park project emphasizes the “five finger principle” in passive ultra-low energy consumption building design, i.e.

Among them, the passive house is located in plot 0062 on the south side of the West plot, and is composed of A2 # on the west side, A5 # on the northwest side and A4 # on the northeast side (Fig.

This prefabrication assembly construction mode determines that the gaps between building components are inevitable, which has a negative impact on the air tightness of the building.

After preliminary energy-saving calculation, the thickness of vacuum insulation board can be controlled below 100mm, and the insulation thickness required for the other three materials is between 200 and 300mm, which is much greater than the insulation thickness of the external wall of ordinary residential buildings.

The three buildings are 6-storey residential buildings, with a total building area of about 10% of the total residential building area of the West plot.

(2) Due to the weak deformation resistance of rigid polyurethane, the heat transfer coefficient of insulation materials is lower than that of graphite polystyrene board after comparing with several extruded polystyrene boards on the market..

(2) The three buildings cover both the north-south direction and the east-west direction.

If sandwich insulation board is used, the thickness of traditional insulation material is large, and the outer blade plate is far from the inner blade plate, the strength requirements of the tie pieces are significantly increased, and more high-strength tie pieces are required to fix, which aggravates the formation of cold bridges.

Precast buildings aim at factory prefabrication and on-site splicing, in order to achieve an efficient and accurate mass construction mode.

The sandwich wall panel fixes the decorative outer leaf plate to the inner leaf plate with tie pieces.

(3) In order to improve the quality and comfort of the residence, the project adopts the floating window; The shapes and moldings of the facade and the roof are rich, and the common design methods of the passive house cannot be simply applied.

If the vacuum insulation board with thin thickness is used, the tie piece may pierce the insulation layer and greatly reduce its insulation capacity.

Therefore, the technical system of precast veneer external wall and external insulation is finally selected for the project.

The combination and application of the two technologies to residential buildings in the northern cold area makes this project more challenging.