Vacuum Glass for Skylights: A High-Performance Glazing Solution

As an important architectural element for introducing natural daylight and enhancing spatial quality, skylights are increasingly used in hotel lobbies, commercial atriums, hospital waiting areas, museum galleries, luxury residences, and other high-end architectural spaces.

However, when conventional insulating glass units (IGUs) are installed horizontally, increased gas convection within the insulating cavity can significantly increase heat transfer. This may result in common skylight problems such as excessive heat gain in summer, heat loss in winter, and condensation or water dripping.

LandVac Titanium Vacuum Glass, or VIG, addresses these challenges through the physical characteristics of its vacuum cavity, where gas convection is eliminated, and thermal performance remains stable regardless of installation orientation. Combined with a vacuum + laminated composite structure and flexible titanium edge-sealing technology, LandVac Titanium Vacuum Glass provides skylights with a comprehensive glazing solution that combines energy efficiency, condensation resistance, safety, slim construction, structural strength, and adaptability to different climates.

These characteristics make vacuum glazing a high-performance option for demanding skylight applications.

Q1: Why does the thermal insulation performance of conventional insulating glass decrease significantly when used in skylights? What are the advantages of vacuum glass for skylights?

A: When an insulating glass unit is installed horizontally, the gas inside the insulating cavity can develop stronger convection currents as it is heated. Heat is transferred more rapidly from the warmer lower surface toward the cooler upper surface, increasing the U-value of the glazing. This is one of the key reasons why conventional IGUs may experience reduced thermal performance when used in skylights.

Test data

A conventional 6 mm + 12A + 6 mm argon-filled coated insulating glass unit was tested in different installation orientations.

Vertical installation: U-value of 1.45 W/(m²·K)

Horizontal installation: U-value increased to 2.14 W/(m²·K)

Performance reduction: approximately 47%

Five advantages of vacuum glass for skylights

1. High energy efficiency with stable thermal performance

The U-value of vacuum glass can be as low as 0.3 W/(m²·K). Its thermal insulation performance can be approximately 2–4 times better than conventional insulating glass, depending on the specific glazing configuration.

Because the vacuum cavity contains no gas, gas convection within the cavity is eliminated. As a result, vacuum glazing is not subject to the same orientation-related convection effects as conventional gas-filled insulating glass, helping maintain stable thermal performance when installed horizontally.

2. Condensation resistance

The vacuum cavity contains no water vapor, while the interior glass surface can maintain a temperature closer to the indoor environment. This helps reduce the risk of condensation and makes vacuum glazing suitable for applications such as hospitals, schools, museums, and other buildings where indoor humidity and environmental stability are important considerations.

3. Safety and wind-load resistance

LandVac uses a vacuum + laminated composite structure for skylight applications. If the glass breaks, the PVB interlayer helps hold the broken glass together and reduces the risk of falling fragments.

The fully tempered glass substrate provides high structural strength, with a tested wind-pressure resistance of up to 7200 Pa.

4. Slim and lightweight construction

A single 8.3 mm LandVac vacuum glass unit can provide thermal insulation performance comparable to that of a much thicker conventional building envelope, while weighing more than 10 kg less per square meter than a typical triple-glazed configuration, depending on the specific glass composition.

Its slim construction can help reduce glazing weight and the associated structural load on a building.

5. Adaptability to different climates and applications

Vacuum glass can be used in different climatic regions, from hot and humid areas such as Hainan to cold regions such as Heilongjiang, as well as in high-altitude environments.

Depending on project requirements, glazing configurations can be customized with options such as Low-E coatings, insulating cavities, and different laminated structures to meet specific climatic, thermal, and architectural requirements.

Q2: How much energy can vacuum glass skylights save?

A: Vacuum glass skylights can significantly improve thermal performance and help reduce cooling loads. Based on the commonly used building-industry estimate that a 1°C increase in indoor temperature may increase air-conditioning energy consumption by approximately 10%, improved thermal control can contribute to a reduction in cooling demand.

Comparative test data

A comparative experiment simulating solar radiation on skylight glazing was conducted at 21 time points between 9:31 and 16:01.

During the heating stage:

The temperature inside the test chamber with conventional insulating glass was approximately 1.0–2.5°C higher than that with vacuum glass on average.

The maximum temperature difference reached 2.53°C.

During the hottest period:

At approximately 2:00 p.m., the maximum temperature difference reached 2.78°C.

During the cooling stage:

The temperature reduction of the vacuum-glass test chamber was 1.35°C smaller than that of the conventional insulating-glass test chamber.

The overall daily temperature fluctuation was reduced by approximately 8%.

For large-volume spaces such as hotel lobbies, hospital atriums, and commercial atriums, improved thermal performance of skylight glazing can contribute to lower HVAC loads and potentially meaningful long-term energy savings. Actual energy and electricity savings will depend on factors such as skylight area, building orientation, climate, HVAC system, glazing configuration, and operating conditions.

Q3: Are vacuum glass skylights safe? Will the glass fall if it breaks?

A: LandVac vacuum glass skylights can be designed with a vacuum + laminated composite structure. If the glass breaks, the PVB interlayer helps retain the broken glass and reduces the risk of falling fragments.

Key safety features

1. Fully tempered glass substrate

The glass substrate is fully tempered and has a tested wind-pressure resistance of up to 7200 Pa. The product has also undergone ATI wind-pressure testing, supporting its application in environments subject to demanding wind and snow loads.

2. Flexible titanium metal edge sealing

LandVac's proprietary flexible titanium metal edge-sealing technology is designed to accommodate thermal expansion and contraction, helping address the cracking and vacuum-leakage risks associated with conventional rigid edge-sealing structures.

3. Long-term durability testing

LandVac Titanium Vacuum Glass has undergone 22,500 hours of accelerated ageing testing, providing test evidence for long-term performance stability.

Why Choose Vacuum Glass for Skylights?

Driven by increasingly stringent energy-efficiency requirements and the demand for higher-quality architecture, skylights are no longer simply architectural elements for introducing natural daylight. They are functional parts of the building envelope that must balance energy efficiency, thermal comfort, condensation resistance, and safety.

LandVac Titanium Vacuum Glass combines the physical advantage of a vacuum cavity without gas convection, the manufacturing reliability of flexible titanium metal edge sealing, and the safety advantages of a vacuum + laminated composite structure.

With its slim profile, high thermal insulation performance, structural strength, and adaptability to different climatic conditions, LandVac Titanium Vacuum Glass provides a high-performance glazing option for skylights in hotel atriums, hospital waiting areas, commercial complexes, museums and cultural venues, luxury residences, and other large-span or high-ceiling spaces.