High performance glass: a "powerful tool" in energy-saving building design

Source: Qianjia.com

The building environment plays an important role in global energy use and climate change. As architects and builders search for ways to reduce the energy footprint of buildings, a promising solution is high-performance glass.

High performance glass refers to the use of advanced window technology to minimize energy consumption in buildings. This is particularly useful in commercial buildings or spatial designs with high window to wall ratio (WWR). These glasses have lower solar thermal gain coefficient (SHGC) and U-value, as well as high visible light transmittance (VLT), thereby improving energy efficiency and occupant comfort.

Introduction to Terminology

To fully understand the advantages of high-performance glass, it is important to understand several key terms:

U-value: This is a measure of the heat flow rate of opening windows (windows, doors, etc.) per unit area when there is a 1-degree temperature difference between one side of the air and the other side of the air. A lower U value means better insulation performance, thereby reducing the need for manual heating or cooling.

Solar thermal gain coefficient (SHGC): This is the ratio of the amount of solar radiation passing through the window to the total amount of solar radiation falling on the window. A lower SHGC means less solar heat absorption, which helps keep buildings cool in hot weather.

Visible light transmittance (VLT): This is an indicator that measures how much visible light is allowed to enter a window. High VLT can increase daylighting, reduce the demand for artificial lighting, and thus reduce energy use.

The Role of High Performance Glass

High performance glass can significantly affect the energy use, visual and thermal comfort of buildings, and even the mental health of residents. Modern efficient glass systems typically consist of two or more glass plates separated by air or low conductivity gas or vacuum in the middle.

By reducing thermal gain (low SHGC) and thermal loss (low U-value), high-performance glass can reduce the demand for heating and cooling, thereby saving energy. In addition, by allowing more natural light to enter (high VLT), the demand for artificial lighting can be reduced, further improving energy efficiency.

A key consideration when selecting glass for buildings is the ratio of light to solar gain (LSG), which is the ratio of light transmittance (VLT) to solar thermal gain coefficient (SHGC). A higher LSG indicates that more light is transmitted into space without adding too much heat. Therefore, it is recommended that builders and end users choose glass based on this ratio.

Different types of glass and their respective U-values:

Please note that these U-values are approximate and may vary depending on the specific product and manufacturer. The smaller the U value, the better the insulation effect. Low-E (low Emissivity) glass has a special coating to minimize the amount of infrared and ultraviolet rays that can pass through the glass without affecting the transmission of visible light.

The following is a thermal load analysis of a 10000 square foot building using single layer glass and low radiation double layer glass. For simplicity, assume that the building is a simple cube, with all faces made of glass and equal distribution of heat load on all faces.

Firstly, it is necessary to clarify some key parameters:

Single layer glass U value: 5.7 W/m ² K

Low-E double-layer glass U-value: 1.4 W/m ² K

Indoor temperature (for cooling): 24 ° C (75.2 ° F)

Outdoor temperature (summer peak): 35 ° C (95 ° F)

Total surface area: 10000 square feet=929 square meters (approximately)

To calculate the heat load, the following formula will be used: heat load=U value x area x temperature difference.

This indicates that using low radiation double-layer glass instead of single-layer glass can significantly reduce the thermal load of buildings, thereby significantly saving energy.

Please note that this is a simplified example where the actual heat load of a building will depend on many other factors, such as building orientation, shading, ventilation, internal heat gain, etc.

In short, high-performance glass is a powerful tool in energy-saving building design. By balancing thermal comfort and visual comfort, it creates a healthier and more comfortable indoor environment, while significantly reducing energy use and related emissions. As we continue to strive for a more sustainable future, solutions such as high-performance glass will become increasingly important in the design and operation of buildings.