Windows are essential components of every building, providing natural light, ventilation, and a connection to the outside environment.

However, windows are also the primary source of energy loss in a building. Poorly insulated windows can cause a significant increase in heating and cooling costs.

A spacer is an important component of the window assembly that plays a critical role in window energy efficiency.

This post explores the different roles that spacers play in window energy efficiency, including their types, features, and how they affect window performance.

What’s A Spacer?

A spacer is a narrow strip of material that separates the panes of glass in a double or triple-pane window. It helps maintain the proper distance between the glass panes and provides structural support to the window unit. Spacers are typically made of aluminum, stainless steel, or composite materials, and they come in various widths and thicknesses.

The primary function of a spacer is to create a sealed air space between the glass panes. This air space acts as an insulating barrier, reducing heat transfer and energy loss through the window. Spacers also play a critical role in preventing the infiltration of moisture, air, and other outdoor elements that can damage the window and reduce its energy efficiency.

Warm Edge Technology (WET)

Warm Edge Technology (WET) is a term used to describe spacers that have been designed to reduce heat loss at the edge of a window. Traditional spacers, such as aluminum or steel, conduct heat readily, leading to significant heat loss at the edge of the glass. This thermal bridging can cause condensation to form, which can lead to mold growth, and it can also reduce the overall energy efficiency of the window.

WET spacers are made of materials that have a lower thermal conductivity than traditional spacers. These materials include foam, rubber, and thermoplastic materials. WET spacers reduce heat loss by minimizing the amount of heat that is conducted from the interior of the building to the exterior through the window frame.

What Is A Perfect Spacer?

A perfect spacer is one that has the following:

1. The Seal

• A perfect spacer should provide an airtight seal between the glass panes, preventing air and moisture infiltration.

• The spacer should have low permeability to gas and water vapor, reducing the risk of condensation and improving energy efficiency.

• The sealant used to bond the spacer to the glass should also be strong, durable, and resistant to degradation over time.

2. Adaptability

• A perfect spacer should be adaptable to different window styles and materials, such as vinyl, aluminum, or wood frames.

• The spacer should be able to accommodate different glass thicknesses and configurations, such as double or triple glazing.

• The design of the spacer should also allow for the expansion and contraction of the glass due to temperature changes.

3. Strength & Durability

• A perfect spacer should be strong enough to support the weight of the glass panes and withstand wind and other external forces.

• The spacer should be durable and long-lasting, with minimal risk of cracking, warping, or corroding over time.

• The material used for the spacer should also be resistant to UV radiation, ozone, and other environmental factors that can degrade the material.

4. Maintaining Temperature Difference

• A perfect spacer should have low thermal conductivity, reducing heat transfer through the window and maintaining a comfortable indoor temperature.

• The design of the spacer should also minimize the temperature difference between the edge of the glass and the interior of the room, reducing the risk of condensation and improving energy efficiency.

5. Keeping It Dry

• A perfect spacer should be designed to keep the interior of the window dry, reducing the risk of mold, rot, and other moisture-related damage.

• The spacer should be able to absorb any moisture that may form within the window and release it back into the air, preventing the buildup of condensation.

Spacer Technology For Different Spacers

Spacer technology has come a long way in recent years, with many different types of spacers available on the market. Here are some of the most common types of spacers and their features:

• Aluminum spacers: These are the most traditional spacers commonly used in older windows. Aluminum spacers are inexpensive and easy to install, but they have a high thermal conductivity, which reduces energy efficiency.

• Stainless steel spacers: Stainless steel spacers have a lower thermal conductivity than aluminum, making them more energy-efficient. They are also more durable than aluminum, but they are more expensive and can be more challenging to install.

• Foam spacers: Foam spacers are made of polyurethane foam and have low thermal conductivity. They are easy to install, cost-effective, and have excellent insulating properties. However, they are not as durable as metal spacers, and they can break down over time.

• Thermoplastic spacers: Thermoplastic spacers are made of materials such as PVC or PET, which have low thermal conductivity. They are easy to install, cost-effective, and have good insulating properties. Thermoplastic spacers are also more environmentally friendly than metal spacers, as they can be recycled. However, they may not be as durable as metal spacers and may deform over time.

• Hybrid spacers: Hybrid spacers are a combination of materials, such as metal and foam or metal and thermoplastic. Hybrid spacers combine the best features of different materials, providing excellent energy efficiency, durability, and ease of installation.

The Width Of A Spacer

The width of a spacer plays an important role in the energy efficiency of a window. The wider the spacer, the more significant the heat loss through the window. A spacer that is too wide can also increase the risk of condensation forming on the inside of the glass, reducing visibility and potentially causing damage to the window frame.

The International Glazing Database (IGDB) recommends a maximum spacer width of 16mm for double-glazed windows and 19mm for triple-glazed windows. These recommendations are based on studies that show that wider spacers can reduce energy efficiency by up to 20%.

Final Thoughts

Spacers play a critical role in window energy efficiency, providing a sealed air space between the glass panes and reducing heat transfer through the window. Warm Edge Technology (WET) spacers have been developed to minimize heat loss at the edge of the glass, improving energy efficiency and reducing the risk of condensation. A perfect spacer should be thermally efficient, structurally sound, long-lasting, and environmentally friendly.

Spacer technology has come a long way, with a wide range of materials and designs available to suit different window styles and applications. The width of a spacer is also an important consideration, as wider spacers can reduce energy efficiency and increase the risk of condensation. By choosing the right spacer for a window, homeowners and builders can maximize energy efficiency, reduce heating and cooling costs, and improve the comfort and safety of their buildings.