- The Darker Side of Glass Roofs - March 11, 2025
- The Dark Side of Panoramic Sunroofs - May 30, 2024
The first installment in this series didve into how modern cars often have panoramic roofs, offering an enhanced driving experience and a sense of luxury. However, these features, while aesthetically appealing, introduce a variety of issues that affect comfort, energy efficiency, and environmental sustainability. This article highlights further overlooked challenges and calls for regulatory measures to address the design flaws compromising vehicle performance. Voice your concern by signing the petition here.
The Function and Appeal of Sunroofs
Sunroofs have long been a desirable feature, providing natural light and ventilation. Traditional sunroofs were small, tinted, and included solid, insulated covers that effectively blocked heat and cold, allowing for efficient regulation of cabin temperature through heating and A/C systems.
The Problem with New Sunroof and Glass Roof Designs
Recent trends in automotive design have introduced larger panoramic and full-glass roofs, enhancing the visual appeal and perceived luxury of cars. However, these new designs have several negative consequences:
- Inadequate Insulation: Modern glass roofs often lack sufficient thermal insulation, replacing solid barriers with mesh or net-like shades. This allows excessive heat transfer in summer and heat loss in winter.
- Increased Energy Consumption: Due to poor insulation, the A/C systems must work harder to cool the cabin in summer and heat it in winter, reducing energy efficiency—particularly problematic for electric vehicles (EVs). For example, Tesla has produced millions of vehicles with glass roofs, potentially wasting $750 million annually in energy costs due to inefficient thermal protection.
- Discomfort for Occupants: In warmer weather, heat radiates down from the dark-tinted glass, making long drives uncomfortable. In colder climates, the lack of insulation makes the cabin colder, requiring more energy to maintain a comfortable temperature.
- Potential Regulatory Oversight: The shift to larger glass roofs may not adhere to existing industry standards or best practices, raising concerns about insufficient regulatory oversight of these design changes.
Case Study: Real-World Experience
During a test drive of a 2022 Volkswagen Golf GTI with a panoramic sunroof, I immediately felt the heat radiating from the roof, even with the A/C on and the sunshade in place. In contrast, my previous Saab 93, with a standard insulated sunroof, maintained a much more comfortable cabin temperature, confirming my suspicion that newer sunroof designs are less effective in regulating temperature.
The Need for Redesign
To address these issues, manufacturers should reconsider their approach to sunroof and glass roof design. Solutions might include:
- Reintroducing insulated covers to prevent excessive heat absorption and loss.
- Improving glass technology, such as multi-layered glass or advanced coatings with insulating properties.
- Regulatory review to assess whether current designs comply with industry standards and enforce new guidelines for consumer comfort and energy efficiency.
Energy Waste and Environmental Impact
The inefficiency of modern sunroofs extends beyond personal discomfort, with significant economic and environmental implications.
Tesla alone has over 7 million vehicles on the road. Assuming each consumes $1,000 worth of electricity annually, this totals $7 billion in electricity consumption. If poorly insulated sunroofs increase A/C usage by just 5%, that amounts to $350 million in additional energy costs. This wasted electricity, primarily generated from fossil fuels, contributes to carbon emissions, harming the environment. To put this into perspective, $350 million worth of electricity could power 350,000 homes annually.
This issue extends beyond Tesla, with other manufacturers like Volkswagen, Audi, and Mini using similar sunroof designs. Some luxury brands, such as Alfa Romeo, have opted for well-insulated roofs, demonstrating that effective alternatives exist.
Scientific Proof Needed
All claims about the impact of glass roofs on energy consumption and comfort must be supported by scientific data. Measurement should confirm whether these design choices lead to excessive heat, cold, discomfort, and environmental impact. If these effects exceed acceptable levels, the car industry must address them, as it has done historically with other design improvements.
Preliminary laser thermometer measurements indicate a thermal performance issue with dark glass roofs. The key concern is energy waste, which has both environmental and economic consequences, especially during the ongoing energy crisis.
Temperature Comparison: Standard vs. Tesla Roof Design
A comparison was conducted between two black cars under identical weather conditions (25°C, sunny day):
| Measurement | Standard Car (Solid Sunroof Cover) | Tesla (Full Glass Roof) |
| Body Temperature | 60–70°C | 60–70°C |
| Roof Temperature | 60–70°C | N/A |
| Glass Temperature | 40–50°C | 60–80°C |
| Interior Temperature | 30–35°C | 45–60°C |
| Ceiling Temperature | 35°C (insulated) | 65–85°C (glass surface) |
Key Findings:
- Both vehicles have similar external body temperatures due to their black color.
- The standard sunroof’s lighter glass absorbs less heat, reducing interior heating.
- The most significant difference is ceiling temperature: the Tesla’s glass ceiling reaches up to 85°C, nearly double that of the standard car’s insulated ceiling.
- This excessive interior heating forces Tesla owners to use more energy to cool the car, reducing efficiency.
Impact of Cold Temperatures on Energy Efficiency
Cold weather exacerbates the design flaw. In winter, uninsulated glass roofs require more energy for heating. A study with a Mini Cooper SE/EV showed the impact of insulation:
| Measurement | Before Insulation Insert | After Insulation Insert |
| Exterior Glass Temp | -5°C | 2°C |
| Interior Glass Temp | -3°C | 8°C |
| Interior Temp After 10 Min (Set to 20°C) | 10°C | 18°C |
| Interior Temp at ceiling/under glass | 11°C | 20°C |
| Exterior temp of glass | -5°C | -5°C |
Observations:
- Uninsulated glass roofs allow excessive heat loss, forcing the heater to work harder.
- Insulation improved temperature retention, leading to more efficient heating.
- Electricity consumption decreased by approximately 8–9% per 100 km.
- The impact on EV range is substantial, as more energy is consumed to maintain comfort.
Table of Contents
The Shocking Reality
The most troubling consequence of the modern sunroof and panoramic roof design is that it wouldn’t be necessary if manufacturers hadn’t made significant design missteps. While full-glass roofs may offer a futuristic aesthetic, their practical flaws outweigh their appeal.
While sleek and modern, the full-glass roof lacks adequate insulation or shading, exposing passengers to extreme temperatures. This increases energy use for air conditioning or heating, undermining the vehicle’s efficiency. Traditional cars have relied on proper roof insulation for over a century, but automakers have compromised on passenger comfort and vehicle efficiency with panoramic and full-glass roofs.
Vehicles like the Volkswagen Golf and MINI Cooper use net-like shades that provide minimal thermal insulation. Tesla’s full-glass-roof vehicles have no insulation at all, exacerbating energy consumption and raising safety concerns in harsh weather conditions. In extreme Canadian winters, inadequate insulation can make a car unusable.
Historically, roof insulation has been a vital component of vehicle design, minimizing the energy required to regulate cabin temperatures. Glass roofs, however, transfer external temperatures directly into the cabin, increasing the load on climate control systems and making driving uncomfortable in severe weather.
It’s worth questioning why roof insulation was abandoned for aesthetic reasons. Was it a cost-saving measure, a design oversight, or an underestimation of insulation’s role in comfort and safety? This decision seems short-sighted and potentially non-compliant with safety regulations. If roof insulation is mandated by industry standards, its removal may be illegal, pointing to regulatory lapses.
The absence of proper insulation has reduced energy efficiency and comfort, while superficial solutions like net-like shades fail to address the core issue of thermal transfer. Automakers must revisit their designs and incorporate effective insulation or offer alternatives that balance aesthetics and functionality. Industry regulators should ensure compliance with safety and environmental standards.
The new sunroof designs, including panoramic and full-glass roofs, have far-reaching consequences—personal, societal, economic, and environmental. From an individual’s perspective, these effects might not seem significant, and many drivers accept the discomfort and higher energy costs as part of owning the car. However, the cumulative impact on energy waste and environmental harm is substantial.
Tesla is just one example; millions of cars with poorly designed roofs contribute to this issue. The total energy waste could amount to hundreds of millions of dollars per year, with the environmental toll further exacerbating the crisis.
Proposed Scientific/Technical Test
To validate the claims of energy waste and thermal inefficiency, a proper scientific test is required. We propose a test involving three sets of cars with identical body colors (preferably black) under controlled conditions (30°C, sunny day, not earlier than 11 am). The test would compare:
- Two standard cars (one with and one without a sunroof), both with proper roof insulation.
- Three current cars with glass roofs: a VW Golf GTI with a sunroof (one-third glass), a VW Tiguan with a panoramic roof (two-thirds glass), and a Tesla with a full glass roof.
The test would measure how much energy each car needs to cool the interior and maintain a comfortable temperature. After this, the cars would be insulated, and the energy required to cool them would be tested again. This test would clearly demonstrate the impact of roof insulation on energy use and vehicle efficiency.
By removing roof insulation, automakers have compromised energy efficiency and contributed to global energy waste. This proposed test will quantify the difference insulation makes in terms of energy consumption and passenger comfort, encouraging automakers to address this design flaw.
What Next?
The rising threat of climate collapse demands that we address the “Dark Side” of glass roofs in vehicles. This design flaw – the failure to properly insulate glass roofs, sunroofs, and panoramic roofs – results in increased energy consumption and discomfort for millions of car owners. Despite widespread awareness of the issue, corporations have shown little interest in resolving it, and governmental or media intervention has been largely absent.
As highlighted in historical examples like Ralph Nader’s Unsafe at Any Speed, regulatory actions can enforce change when manufacturers neglect consumer safety. Yet, modern automakers continue to ignore the harmful effects of poorly insulated glass roofs, seemingly without fear of public or government backlash. This lack of accountability raises a crucial question: will we see a new advocate or organization step forward to hold these companies accountable and demand the necessary changes?
The Solution: Insulation
The root cause of the problem lies in poor design – specifically, the failure to replace traditional insulation with effective thermal materials beneath the glass roofs. This oversight leads to excess heat or cold entering the car, forcing air conditioning and heating systems to work harder and wasting energy. The solution is simple: manufacturers must incorporate proper insulation into the roof designs. This would restore energy efficiency, reduce discomfort, and help mitigate the environmental impact of vehicle energy consumption.
Why Insulation Matters
Proper insulation has always been key to regulating interior temperatures in cars. Older vehicles were well-insulated, ensuring comfort regardless of external conditions. However, modern glass roofs lack this protection, leading to extreme internal temperatures and higher energy use. With escalating environmental concerns and an ongoing energy crisis, wasting energy in this way is no longer acceptable. Insulating car roofs will reduce energy consumption and improve the comfort of vehicle occupants.
Making Cars Energy Efficient Again
The solution is straightforward and cost-effective. Manufacturers should replace the current net-like shades under glass roofs with thermal materials. This would restore the energy efficiency that traditional insulated roofs offered and reduce the need for excess heating or cooling. Just as homes have been required to adopt energy-efficient measures, vehicles should follow suit.
Addressing Existing Vehicles
For those who already own vehicles with poorly insulated glass roofs, aftermarket solutions are available. These solutions, such as thermal covers or insulating materials, can help reduce interior temperatures and energy consumption. Despite the lack of action from manufacturers, the aftermarket industry has stepped in to fill the gap.
The Case for Full Glass Roofs
Full glass roofs, like those found in Tesla and Lucid vehicles, offer an appealing aesthetic but create significant discomfort for occupants due to extreme heat buildup. While aftermarket products can provide some relief, they do not offer the same protection as traditional roof insulation. Tesla, despite its reputation for energy efficiency, has yet to address this design flaw, leaving consumers to pay for fixes that should be incorporated into the vehicles from the start.
Panoramic and Sunroofs: A Common Problem
Other brands, including Volkswagen, BMW, and Jaguar, also produce vehicles with sunroofs or panoramic glass roofs. These designs often feature minimal shading, leaving occupants exposed to heat or cold. Though some owners have developed homemade solutions, the fact that such modifications are necessary highlights the oversight by manufacturers. Why should consumers bear the cost of fixes when automakers could address the problem at the production stage?
Regulatory Response
It is time for regulatory authorities to step in. The failure to insulate glass roofs is not only an issue of consumer comfort but also of environmental impact. Historical precedents, such as the Volkswagen emissions scandal, show that government intervention can force manufacturers to address systemic flaws. This issue deserves similar attention, as it affects millions of consumers and contributes to unnecessary environmental degradation.
We call on governments, regulatory bodies, and industry leaders to take immediate action. Proper insulation in glass roofs is essential for improving vehicle efficiency, reducing energy consumption, and protecting the environment. Ignoring this issue would be a failure to protect both consumers and the planet.
If you are responsible for transportation or environmental policy, please take this report seriously. We need collective action to ensure that the automotive industry embraces sustainable and efficient practices for the future. Sign the petition now to tell car manufactures it’s time to improve their product design with simple and efficient insulated shade features to reduce wasted energy consumption.
