Glass Energy & Performance

Introduction

Sunlight and views are vital to psychological well being. Many studies have shown evidence that people generally do better in sunlight and with views across nature; this includes doing better on tests, working more efficiently, and recovering from health issues faster. While there are many benefits to glazing in a building, the glass can be a major source of heat loss and heat gain in a building.

Why Glass Matters

Glass allows solar energy to enter the building, and this energy can be used as a source of natural heating during the colder months. But glass has a high initial cost, high maintenance, and rapid heat loss, up to 20 times greater than an insulated wall. The glass area of the building is one of the most critical elements as far as heat gain and heat loss are concerned.

• Disadvantages of glazing can be partially overcome by using multiple panes of glazing, heat absorbing or reflecting glass, sun control devices, and the use of smaller window openings.
• Daylighting: A passive design strategy that combines natural sunlight with dimmed overhead lighting to reduce energy costs and indoor lighting heat loads.
• There are also secondary benefits to systems. For example, letting in more natural daylight, reduces the need for mechanical lighting in the space. And therefore less heat will be generated by the lighting system, meaning there is a lower need for air conditioning in the space.
• This article does not go into it, but there are various well documented benefits of natural light for humans.

Fenestration: Name for any opening in a wall or the building's envelope in particular. Typically this is used in context when speaking about the glass in windows or doors.