Retrofitting Solar Shading to Enhance Energy Efficiency

Featured image from Josh Sorenson on Pexels.

Solar shading is a smart, passive design strategy that regulates the amount of sunlight entering a building.

By controlling sunlight, solar shading reduces reliance on energy-intensive cooling systems and promotes a more sustainable, cost-effective building operation.

In the UK, where older buildings often grapple with poor thermal performance, retrofitting solar shading systems is more critical than ever.

Rising energy costs and stricter regulations, like the UK’s Approved Document O (2022), emphasise the need for passive cooling solutions to combat overheating.

Retrofitting isn’t just about ticking regulatory boxes—it’s about future-proofing your building to meet modern demands for energy efficiency and occupant comfort.

Why Retrofitting Matters

Existing buildings form the majority of the UK’s built environment.

Unlike new builds, which integrate modern energy-saving technologies from the ground up, older structures often lack adequate thermal controls.

Solar shading offers a practical, non-intrusive way to retrofit these buildings, reducing cooling loads by up to 30% and improving occupant well-being with better lighting and temperature control.

At Enviroscreen, we bring over 30 years of experience in designing and installing bespoke solar shading solutions.

Whether you’re working on an office block, school, healthcare facility, or heritage site, we understand the unique challenges that retrofitting presents.

From initial concept through to installation, we provide tailored solutions that integrate seamlessly with your structure. And because we prioritise sustainability, our products are designed to maximise energy efficiency while maintaining architectural harmony.

We make retrofitting solar shading simple, effective and impactful.

Benefits of Retrofitting Solar Shading

Energy Efficiency

Retrofitting solar shading systems significantly reduces solar heat gain, cutting down on the need for energy-intensive cooling.

By preventing excess heat from entering a building, shading reduces the workload on HVAC systems, leading to substantial energy savings.

In fact, studies have shown that retrofitting can reduce annual cooling energy consumption by 5% to 30%. For more detailed insights, the Energy Institute highlights these savings in their research.

This reduction not only lowers your energy bills but also contributes to your building’s overall sustainability goals, helping you meet stricter energy regulations like the UK’s Part L standards for energy efficiency.

Occupant Comfort

By reducing glare and controlling contrast, shading systems improve the quality of natural light within a building.

Occupants benefit from a more visually comfortable environment, whether it’s a workspace, classroom, or healthcare facility.

Controlled daylight enhances focus, reduces eye strain, and maintains a steady indoor temperature, ensuring year-round comfort.

Aesthetic Enhancements

Beyond the functional benefits, solar shading can transform a building’s appearance.

Well-designed shading devices, like brise soleil or louvres, add architectural interest to façades.

They break up large, uninviting surfaces, giving your building a more human scale while maintaining its functionality.

Custom shading solutions also offer opportunities to align with your aesthetic goals—whether it’s preserving the integrity of a heritage structure or enhancing the sleek look of a contemporary office.

Types of Solar Shading Systems

Fixed Shading Devices

Fixed shading systems offer permanent solutions for controlling solar heat gain.

These systems, such as overhangs, vertical fins and brise soleil, are particularly effective for retrofitting older UK buildings.

Their efficiency depends on factors like building orientation, climate and thoughtful design integration.

1. Overhangs

Advantages:

• Optimised for south-facing façades: Overhangs block high-angle summer sun while allowing low-angle winter sunlight, ensuring year-round thermal balance. Learn more about their benefits.
• Cost-effective and low maintenance: Simple horizontal structures, such as canopies, are easy to maintain and complement traditional UK architectural styles. Find design insights here.
• Compliant with regulations: Overhangs align with Approved Document O (2022), which promotes passive cooling for retrofits.

Limitations:

• Orientation-specific: Overhangs are less effective for east or west-facing façades, which may require vertical shading.
• Design sensitivity: Material and design choices need careful consideration for heritage structures.

2. Vertical Fins

Advantages:

• Ideal for east/west orientations: Vertical fins effectively block low-angle morning and afternoon sunlight, common during UK summers.
• Modular design: Vertical fins can be retrofitted without major structural alterations.
• Enhanced daylight control: Angled fins allow for better natural light diffusion while minimising glare.

Limitations:

• Structural reinforcement: Fins exposed to wind may require added support, particularly in coastal areas.
• Ongoing maintenance: Materials like timber need regular upkeep to resist the damp UK climate.

3. Brise Soleil

Advantages:

• Seasonal adaptability: Angled louvres block high summer sun while allowing winter sunlight, maintaining optimal energy performance throughout the year.
• Architectural appeal: Brise soleil systems, whether curved aluminium or cedar louvres, elevate the aesthetic quality of building façades.
• Energy efficiency: By reducing reliance on cooling systems, they cut HVAC energy use by approximately 30%.

Limitations:

• Installation complexity: Retrofitting requires careful structural assessments to ensure load-bearing capacity.
• Higher upfront costs: While initial investment can be significant, long-term energy savings justify the expense.

Dynamic Shading Devices

Dynamic shading systems adjust in response to sunlight, offering enhanced flexibility for energy efficiency and comfort.

These include internal solutions like motorised blinds and external options like retractable awnings and motorised louvres.

1. Internal Dynamic Shading

Advantages:

• User-friendly control: Smart blinds adjust automatically using sensors, timers, or apps, offering convenience and flexibility.
• Lower installation costs: Avoiding structural changes makes internal systems ~50% more cost-effective than external options.
• Protected lifespan: Internal systems are shielded from weather, reducing maintenance needs.

Limitations:

• Thermal limitations: Internal systems reflect heat only after it enters through glazing, making them less efficient than external alternatives.
• Glare challenges: Internal blinds are less effective at managing glare from low-angle sun.

2. External Dynamic Shading

Advantages:

• Superior heat control: External systems block heat before it penetrates the building, cutting cooling loads by 40–70%.
• Improved glare reduction: Motorised louvres and awnings adjust dynamically to maintain consistent daylight levels.
• Seasonal adaptability: Retractable systems allow winter sunlight for passive heating.

Limitations:

• Higher costs: Motorisation and weather-resistant materials significantly increase upfront investment.
• Weather exposure: UK’s damp, windy climate necessitates regular inspections and maintenance.

Performance Comparison

Metric	Internal Shading	External Shading
Heat Gain Reduction	~14–37%	~60–85%
Cooling Load Reduction	~15–30%	~40–70%
Maintenance Frequency	Low (every 2–3 years)	High (annual inspections)
Aesthetic Impact	Minimal	High (façade alteration)

Both fixed and dynamic shading systems offer unique benefits depending on the building’s design, orientation and usage.

Combining these systems in hybrid solutions can optimise comfort and energy efficiency for UK retrofits.

Window Films and Solar Control Glazing

Window films offer an efficient and cost-effective solution for retrofitting existing windows to improve energy efficiency.

By enhancing solar reflectance and reducing ultraviolet (UV) penetration, these films effectively mitigate solar heat gain, a common challenge in the UK’s temperate climate where glazing often exacerbates summer overheating.

A 2019 study conducted on a hotel in Reading, UK, demonstrated the significant impact of window films, such as Thinsulate Climate Control film, and Low-E double-glazed units (DGU).

The findings included:

• Cooling energy reduction: Both Thinsulate films and Low-E DGU achieved a ~20% reduction in cooling energy use, with total energy savings of 2.7% and 4%, respectively.
• Solar heat gain reduction: Thinsulate films reduced solar heat gain by 35%, while Low-E DGU achieved a 40% reduction.
• Lighting impact: Although light transmittance was reduced by 20%, there was no increased reliance on artificial lighting, as occupancy patterns (e.g., guestrooms unoccupied during daylight) offset any drawbacks.

These results underscore how modest reductions in solar transmission can lead to significant HVAC savings without compromising occupant comfort.

For more details, see the research on Sustainability MDPI and additional insights.

Performance of Sun Control Window Films

When tested in a UK reference building, sun control films showed even greater potential:

• Infrared rejection: Up to 97%, resulting in a 60% reduction in heat gain.
• Energy and CO₂ savings: Simulations predicted annual energy savings of 15–20% for cooling in mixed climates, with a payback period of 10–15 years.
• Enhanced functionality: High transparency ensured no interference with Wi-Fi signals or natural light quality while adding safety benefits like improved shatter resistance.

Window films also work effectively as part of a dynamic shading strategy:

• Low-E films with standard glazing: This combination can rival the performance of high-performance solar-control glass at a fraction of the cost.
• Orientation considerations: South-facing windows benefit most from films, with studies indicating reductions of up to 44% in peak cooling loads.

Window films provide a practical, non-invasive option for retrofitting energy-efficient shading.

Their ability to integrate seamlessly with existing glazing systems makes them a flexible solution for various building types across the UK.

Key Considerations for Retrofits

When retrofitting solar shading systems, several factors must be carefully evaluated to ensure performance, compliance and long-term value.

1. Climate Adaptability

• Southern England: In regions with warmer summers, external shading systems like brise soleil or motorised louvres excel at mitigating overheating. However, retractable designs may be necessary in northern areas to allow winter sunlight for passive heating.
• Unpredictable UK weather: Internal systems with adaptive algorithms, such as glare-based controls or occupancy-linked adjustments, are ideal for managing variable conditions without manual intervention.

2. Integration with Smart Systems

• Internal shading: Pair internal systems with IoT-enabled sensors for real-time adjustments based on occupancy patterns or daylight levels. For example, blinds can automatically close during peak sunlight hours or after work hours to optimise energy savings.
• External shading: Advanced external systems can incorporate weather APIs for automation, retracting shading devices during storms to prevent damage while maintaining energy efficiency.

3. Energy Standards Compliance

• External systems: Fixed and dynamic external shading solutions align with Part L (2022) requirements for passive cooling, reducing the need for mechanical HVAC systems.
• Internal systems: While easier to retrofit, internal shading may need to be complemented by HVAC upgrades to fully comply with energy efficiency standards.

4. Structural Assessment

• Evaluate the building’s sub-structure and fixing points to ensure they can support the additional load of shading devices. This is especially critical for older buildings, where structural reinforcements may be necessary.
• Conduct physical testing and assessments during the planning phase to identify potential challenges and ensure the retrofit is both safe and effective.

5. Building Orientation and Climate

• Geographical location: Tailor shading solutions to the specific climate conditions of the building’s region. For example, buildings in southern England may prioritise fixed external shading, while northern areas may benefit from dual-function systems.
• Façade orientation: South-facing façades are best suited for horizontal shading devices like overhangs, while east- and west-facing façades may require vertical fins or adjustable shading to block low-angle sunlight.

For UK retrofits, external dynamic shading delivers the highest energy performance but comes with greater upfront costs and maintenance requirements.

Conversely, internal systems offer a more budget-friendly and straightforward solution but may compromise thermal efficiency.

Hybrid solutions, such as combining external louvres with automated internal blinds, strike a balance between comfort, energy savings and adaptability—making them an optimal choice for mixed-use buildings.

The Role of Solar Shading in Passivhaus Design

Solar shading plays a pivotal role in achieving Passivhaus standards, which focus on energy savings and occupant comfort.

Fixed and dynamic shading systems are essential for controlling overheating, especially in summer.

By blocking excess heat while allowing natural light, shading systems reduce reliance on air conditioning and maintain optimal indoor temperatures.

This not only improves energy efficiency but also ensures consistent thermal comfort, a cornerstone of Passivhaus principles.

Challenges and Solutions to Retrofitting

1. Design Integration

Challenge: Solar shading systems, especially external devices like brise soleil or overhangs, may conflict with a building’s existing design, particularly for heritage or conservation properties.

Solution: Use customisable materials like timber or neutral-coloured aluminium to align with traditional aesthetics.

2. Cost Considerations

Challenge: Retrofitting shading systems often requires a significant initial investment, especially for bespoke or dynamic solutions.

Solution: Highlight the long-term savings. For instance, brise soleil systems can reduce cooling energy demands by up to 30%, often recouping installation costs within 10–15 years. For budget-conscious projects, hybrid solutions (e.g., external shading with internal automated blinds) can strike a balance between performance and cost.

3. Maintenance Requirements

Challenge: External systems like motorised louvres or vertical fins are exposed to weather conditions, increasing maintenance demands. Similarly, materials like timber may require regular treatment in damp climates.

Solution: Choose low-maintenance materials, such as anodised aluminium, for durability. Develop a maintenance schedule that includes annual inspections for external systems and periodic adjustments for motorised components to ensure sustained performance.

By addressing these challenges with strategic design, cost analysis and planned upkeep, retrofitting solar shading systems can deliver lasting energy efficiency and occupant comfort.

Conclusion

Retrofitting buildings with solar shading is a practical and impactful way to enhance energy efficiency, improve occupant comfort and future-proof structures against rising energy costs and climate challenges.

Whether it’s fixed solutions like overhangs and brise soleil or dynamic systems like motorised blinds and automated louvres, solar shading offers flexible options tailored to a building’s unique needs.

Key benefits include:

• Energy Efficiency: Solar shading can reduce cooling energy consumption by 5% to 30%, with external dynamic systems cutting cooling loads by up to 70%.
• Occupant Comfort: By controlling glare, reducing heat gain and maintaining steady indoor temperatures, shading systems significantly enhance visual and thermal comfort.
• Aesthetic Enhancements: Bespoke shading devices add architectural interest while maintaining the functional integrity of a building.

Best statistics to consider:

• External shading reduces solar heat gain by 60–85%, while internal solutions block up to 37% of heat.
• Studies have shown window films can achieve 20% cooling energy savings and reduce solar heat gain by 35–40%, making them a cost-effective alternative or complement to shading systems.
• Retrofitting solar shading can deliver energy payback within 10–15 years, making it a long-term investment in sustainability.

For building owners and designers, assessing the potential of solar shading retrofits is more than a compliance measure—it’s a step toward a more efficient and comfortable built environment.

Start by evaluating your building’s orientation, climate and structural readiness to identify the best shading solution for your needs.

How Enviroscreen Can Help

At Enviroscreen, we specialise in providing tailored solar shading solutions for retrofitting projects.

With over 30 years of experience, we’ve worked on everything from schools and healthcare facilities to commercial and heritage properties.

Our end-to-end service includes consultation, design, fabrication and installation, ensuring that every solution is customised to your building’s unique requirements.

We also ensure compliance with UK energy regulations, including Part L and Approved Document O, while delivering visually stunning designs that align with your building’s aesthetic.

Let us help you transform your building into an energy-efficient, comfortable and future-proof space.

FAQ: Retrofitting Solar Shading

What is the most cost-effective solar shading retrofit solution?

Window films are a budget-friendly option, reducing solar heat gain by up to 40%. Internal shading, like automated blinds, is another cost-effective solution that avoids structural modifications.

How long does it take to see a return on investment (ROI) for solar shading?

ROI typically ranges between 10 to 15 years, depending on the system type and energy savings achieved. Dynamic systems offer faster payback in energy-intensive buildings.

Can solar shading be retrofitted to heritage buildings?

Yes, but careful planning is required to maintain architectural integrity. Materials like timber or neutral-coloured aluminium can help blend shading devices with heritage aesthetics.

Which solar shading system works best for mixed climates?

External dynamic systems like motorised louvres or brise soleil with retractable features are ideal for mixed climates, as they adapt to seasonal changes and varying sunlight angles.

Do solar shading systems require regular maintenance?

External systems may require annual inspections, particularly in exposed locations, while internal systems typically need minimal upkeep, such as occasional cleaning or recalibration of sensors.

How does solar shading affect compliance with UK energy standards?

External shading aligns with Part L (2022) for passive cooling, helping reduce reliance on HVAC systems. Internal shading may need to be paired with other upgrades to meet compliance fully.