Analysis on energy saving development of the hotte

2022-08-08
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Analysis on the development of glass curtain wall energy conservation

the building energy consumption in China is two to three times that of developed countries with the same climatic conditions. In the process of building a well-off society in an all-round way, the task of energy conservation and emission reduction is very arduous. Building energy conservation is the basis of improving residential comfort and reducing use costs, and it is also an urgent requirement of sustainable development. Only by putting resource conservation and reducing energy consumption in a prominent position, can we better promote the construction of a harmonious society

65% of building energy saving is mainly borne by building envelope system. In the outer enclosure structure, as a major feature of modern architecture, glass curtain wall was widely used in China's Construction Engineering in the 1990s, but there are also many problems, such as the improper selection of glass, resulting in the solar energy through glass in summer is several times that of other material walls; The selected sealant has poor bonding effect, the glue joint construction is not in place, the glue strip is not sealed tightly, and the structural deformation produces cracks, resulting in serious cold and hot air infiltration; The profiles, thermal insulation materials and filling materials used are unreasonable, the node practices are incorrect, and gaskets are not effectively set between components, resulting in large indoor heat loss; In addition, the light pollution caused by the light reflected by the glass and the unstable structure have become the "time bomb" in the air. After entering the 21st century, glass curtain wall engineering is no longer favored by people as before, and its scope of use is limited and the amount of use is reduced

in order to avoid the above common quality problems, the author of this paper, based on more than ten years of working experience in energy saving of glass curtain wall, now analyzes it from two aspects for everyone to discuss

I. energy saving of glass curtain wall

considering the construction cost, some construction units and design units use materials to construct ordinary glass curtain walls. In order to achieve the maximum energy saving of this glass curtain wall project, all participants in the project are required to carefully design, carefully construct and strictly manage in accordance with the technical code for glass curtain wall engineering (JGJ102-2003) and relevant technical standards and relevant provisions on energy saving, so as to ensure energy saving

design

fully consider the thermal insulation, heat insulation and sealing performance of the glass curtain wall project, and select materials with sufficient strength and stiffness to prevent the glass curtain wall from deformation and cracks under the loads of typhoon, earthquake and self weight

material selection

try to use coated glass, because its coating can effectively prevent solar energy from radiating indoors. If a single piece of coated glass is used, products produced by thermal spraying method should be used (the coating is firm and durable). The thickness of the glass is related to the structural safety, but also affects the transmission of heat energy. When the frame supporting curtain wall is used, the thickness of a single piece of glass should not be less than 6mm, and the thickness of a single piece of laminated glass should not be less than 5mm

thermal insulation materials play an important role in energy conservation, while strengthening the fire prevention function. Rock wool, mineral wool, glass wool, etc. should be used as thermal insulation materials for curtain wall works, which has the advantage of good thermal insulation performance and thermal conductivity of only 0. 044w/(m · K), the maximum operating temperature reaches 650 ℃

neutral silicone structural sealant must be used for structural bonding between glass and aluminum profile subframe. This structural sealant has stable performance (the service temperature is -48-88 ℃, the heat resistance is up to 150 ℃, the cold deformation is not obvious), and the bonding force is strong. However, when coated glass is used for full glass curtain wall and point support curtain wall, acidic silicone structural sealant should not be used for bonding (the metal elements contained in the coating react with the acid glue, and the actual operation and data processing method of the experiment comply with the provisions of the national standard gb/t 228 (2) 010 "indoor temperature tensile test method of metal composites", resulting in bond failure)

the weather resistant sealant shall be silicone construction sealant. Silicone sealant has good UV resistance, so it is durable, not suitable for aging and cracking, and has good compatibility with silicone structural adhesive, glass and other components, with good bonding effect

the density shall not be greater than 0 at the joint between glass and glass, profile groove wall. 037g/cm 3 polyethylene foam rod is used as filling material, which is light in weight and has good heat preservation performance

the peripheral gap of the opening window of the glass curtain wall and the gap between the exposed frame curtain wall glass and the profile should be sealed with EPDM, neoprene or silicone rubber, of which silicone rubber (good weather resistance, characterization and engineering utilization; small permanent deformation) has the best quality. This point is easy to be ignored in curtain wall engineering, and people think that the rubber strip has little effect. In fact, if the rubber strip is aged, serious problems such as water leakage and ventilation will occur, affecting the thermal insulation effect of the curtain wall

node method

the opening part of the window is the weak link of thermal insulation in the glass curtain wall. According to the air permeability test data, under the same pressure difference, the air permeability of the openable part is much greater than that of the fixed part. Therefore, the opening angle of the opening window should not be greater than 30 °, and the opening distance should not be greater than 300mm. At the same time, it should be noted that the number of opening windows should not be too large and the area should not be too large in the facade grid design

at the contact of different metal materials (such as between the connector and the main column), insulating gaskets should be reasonably set for isolation. Setting insulating gaskets can prevent electrochemical corrosion, and indirectly play a role in heat insulation

flexible gaskets are set at the contact between the column and the beam. A gap of 1-2 mm can be reserved between the two ends of the beam and the column, and the gap is filled with glue. This practice is conducive to reducing the noise of curtain walls, and also plays a role in heat insulation (semi hidden frame and exposed frame glass curtain walls have a more obvious role due to the exposure of profiles)

when the hidden frame curtain wall adopts the hook type connection to fix the glass components, the hook surface should be set with flexible gaskets, and the elastic cushion block should be used between the lower end of the glass of the open frame and full glass curtain wall and the metal groove. On the one hand, the use of gaskets and cushion blocks can prevent the stress concentration caused by the hard contact between the glass and the hook, resulting in the cracking of the glass, on the other hand, it also has the function of heat breaking

thermal insulation materials shall be set at the gap between the glass curtain wall and the surrounding components, the edge of the opening of the solid wall, the outer edge of the floor or partition wall, and effective sealing design shall be carried out to ensure the thermal insulation performance of the glass curtain wall

the unit plate of the glass curtain wall should not cross the deformation joint of the main building. Reasonable structural measures should be taken for the curtain wall at the deformation joint of the main building to meet the requirements of building deformation. Some glass curtain wall projects have been improperly designed for the curtain wall structure at the deformation joint. Less than a year after they are put into use, due to the construction of fatigue testing machines - equipment measurement problems, the main body settlement and temperature expansion are affected. Here, the curtain wall cracks and damages, resulting in water leakage and air permeability

calculation sheet

calculate the loads that may occur simultaneously in the structure during the use of the glass curtain wall, carry out the load combination according to the limit state of bearing capacity and the limit state of normal use, and take their most unfavorable combination for calculation, and select the materials whose strength and stiffness meet the requirements. In the most unfavorable state, curtain wall materials can only have elastic deformation, not plastic deformation

the most basic formula for calculation: r0s ≤ R (R0 is the important coefficient of the structure, s is the combined value of load effect, and R is the resistance of the structure)

filing and joint review of construction drawings

the construction administrative department should strengthen the supervision of energy conservation of glass curtain wall engineering, and review and record the construction drawings. Before the construction of the project, the construction unit shall organize the technicians of all parties involved in the construction to review the construction drawings, so as to improve the design content and meet the requirements of curtain wall materials and node construction

construction

according to the requirements of design documents, specifications and inspection and evaluation standards, do a good job in pre construction preparation, quality control of each process and each node in construction, and ensure the acceptance of the project

preparation before construction

carefully read the design documents, review whether the material selection is appropriate, whether the node practice is correct, and whether the calculation content is reasonable, and feed back the opinions to the designer in time

retest the place where the glass curtain wall is to be installed in the built main structure, and make necessary adjustments to the division size of the curtain wall design facade according to the measured results to prevent the accumulation of errors from causing excessive joints

prepare the construction organization design, the content should be comprehensive and targeted, and the construction measures in energy conservation should meet the requirements

carry out pre job training and technical disclosure for engineering construction personnel, and make key disclosure on the content of energy-saving operation

organize the mobilization of materials, and check whether the specification, model and performance of main materials, components and accessories are consistent with the requirements of design documents, and whether the certificate of conformity, inspection report and quality assurance are complete

in the construction stage, the flexible gaskets and blocks at the joints of metal materials and components and fittings should be set in place, and the joints between the upper and lower ends of the columns and the main structure should be sealed with glue

the temperature, humidity and sanitation of the structural adhesive construction workshop should meet the requirements, the construction of structural adhesive should be standardized, and the curing conditions and curing time after construction should meet the requirements

the sealing rock wool (mineral wool) between the curtain wall and the outer edge of each floor slab and partition wall should be filled tightly, and the thickness should not be less than 100mm. Some people think that 1 is set between the upper and lower floors. 5mm galvanized steel plate is used as the lining plate, and rock wool is placed on it to form a fireproof layer. In case of fire, the steel plate burns through the rock wool and then falls off, so it is of little significance to put rock wool here. This idea is incorrect, because rock wool can effectively improve the thermal insulation performance

the gaps left around the curtain wall glass and between the interior and exterior finishes of the building should be filled and sealed with flexible materials

the gap between the upper and lower beams, side columns and the main structure should be filled with foaming agent before decorative treatment

if the insulation material used has no moisture-proof performance, it shall not be used after being affected by moisture. During the construction of the project, it is often encountered that the thermal insulation materials are not effectively covered in time after being filled, that water enters in rainy days, that the thermal insulation materials are damp when being transported in rainy days, or that the storage yard is unreasonably set and soaked in water, which significantly reduces the thermal insulation performance of the materials. Therefore, moisture-proof measures should be taken during construction to ensure the thermal insulation performance of the thermal insulation materials

two rubber strips are used to seal between the opening window sash and the frame. The splicing of the rubber strips should be tight (the joints can be sealed with glue), and the corner splicing of the window frame material should be sealed with glue

the glass gluing surface shall be cleaned before the construction of weatherproof glue. Pay attention not to apply weather proof glue at night or in rainy days. When applying weather proof glue in the joint, it should be bonded on two sides instead of three sides (if three sides are bonded, the weather proof glue will be torn after repeated tension and compression, thus losing its sealing effect). Its construction width should not be less than 2 times of the construction thickness

project acceptance

the construction party shall carry out self inspection on the quality of each process to ensure that the quality of the previous process meets the requirements before the construction of the next process. After the installation of curtain wall beams and columns, the personnel of the construction, supervision, design and construction parties shall jointly conduct intermediate acceptance, and the special completion acceptance of the project shall be carried out after the completion of the project. At present, the requirements of local construction administrative departments are different. Some places require special acceptance of glass curtain wall projects, while others do not. In fact, it is necessary to carry out special acceptance of glass curtain wall project. During the special acceptance, we should check how the energy-saving work is completed, and put forward rectification suggestions for defective parts. The construction unit shall completely complete the rectification of the quality problems raised in the project acceptance, and the supervision unit shall re inspect the rectification until it meets the requirements

project re inspection and test

witness the sampling of main materials entering the site and send them to the laboratory for re inspection. At present, this work is not done enough, and the structural adhesive of some projects is only made by the factory

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