STUDY ON PERFORMANCE OF INSULATING GLASS WITH BUILT-IN LOUVERS IN BUILDINGS

. This paper mainly studies the shading problem of shutters in typical rooms of buildings in winter. In order to further study the performance of the built-in louver insulating glass, the built-in louver insulating glass was simulated under the standard operating conditions and throughout the year through software such as THERM and Windows, and the key parameters such as total heat transfer coefficient, solar transmittance, and solar heat gain coefficient were obtained. The heat transfer coefficients of the built-in louver insulating glass when the louvers are placed at 0°, 45°, 90°, -45° and without louvers are 3 W/m2•K, 2.75 W/m2•K, 2.38 W/m2•, respectively. K, 2.55 W/m2•K and 2.66 W/m2•K. The solar transmittance of the built-in louver insulating glass at different angles of the louver is obtained. The maximum value is 0° and no louver, followed by the angles of 45° and -45°. Zero at 90°.


Introduction
The thermal performance of the window is the worst among the three building envelope components, and it is one of the most important factors affecting the indoor thermal environment and building energy consumption.
Because traditional cloth curtains fail to block the heat outside the envelope structure in summer, Therefore, more and more buildings will consider using energy-saving exterior windows in the future. The new type of louvered shading glass is rich in functions and can be adjusted, the shading ability can be adjusted in summer, and the window insulation can be increased in winter, and it is gradually applied in the office and residential fields. In the theoretical research of louver shading, foreign research is relatively mature. Klems [1][2] [3] and Wright [4] have fully studied the theoretical calculation of the solar heat gain coefficient of louver shading, and obtained the calculation formula. Simulation study on optical and thermal performance of inner sunshade. Deng Tianfu obtained through simulation that active external shading can reduce HVAC energy consumption [5] and increase lighting energy consumption [6] . Zhang Qiang [7] used DOE-2IN simulation to obtain the shading coefficient of Chongqing's exterior windows ranging from 0.26 to 0.46, and the optimal heat transfer coefficient was 1.9 to 2.5 W/m2•K. Wang Yunxin [8] used WINDOW to calculate that the built-in louver insulating glass is more suitable for areas with hot summer and cold winter. Optical and thermal performance analysis of inner sunshade for experimental study. The measured solar heat gain coefficient decreases as the shutters are closed [8] . Guo Xiaoqin [9] used experiments to test the solar transmittance under different louver inclination angles.

Built-in louver insulating glass window model
The built-in louver insulating glass window is shown in Figure 1. The difference between it and ordinary double-layer insulating glass is that the louver is placed between the two glasses, which has the functions of shading and anti-glare.

Introduction of built-in louver insulating glass window
The fixed shading device can reduce the solar radiation heat gain in summer and also reduce the solar radiation heat gain in winter. The new built-in louver insulating glass has the feature of adjustable middle louver.
Window radiative heat gain and convective heat transfer have a significant impact.
The difference between the built-in louver insulating glass window and the ordinary double-layer insulating glass is that the louver is placed between the two glasses, which has the functions of shading and anti-glare. The adjustment block on the right can adjust the retraction degree of the louver, and the adjustment block on the left can adjust the angle of the louver. Compared with traditional cloth curtains, it can block solar radiation to the outside, and does not require periodic cleaning, and there is no need to consider fire hazards.

Calculation model of total heat transfer coefficient and light transmission performance
According to GBT 22476-2008 Section 6.5.1, the heat flow meter method was formulated to measure the total heat transfer coefficient in this experiment.
In this formula, R is the thermal resistance of the insulating glass, m2•K/W; T1 is the average temperature of the hot surface of the sample, K; T2 is the average temperature of the cold surface of the sample, K; Heating average power, W In this formula, He is the outdoor surface heat transfer coefficient, W/m2•K; Hi is the indoor surface heat The solar transmittance is calculated according to Equation 9 in Section 3.4 of GBT 2680-1994.
In this formula, Sλ is the relative spectral distribution of solar radiation; τ(λ) is the solar spectral transmittance of the sample.    WINDOW is a commonly used glass simulation software, which can simulate and calculate the parameters listed in Table 3.

Tsol
The ratio of the intensity of solar energy directly transmitted through glass to the intensity of incident solar energy in the wavelength range from 300 nm to 2500 nm

Results
This chapter uses WINDOW software to simulate and analyze the built-in louver insulating glass.
WINDOW is a commonly used glass simulation software.
The    Table 4.