Ordsall Surgery
Reducing overheating and avoiding air conditioning through solar-control reglazing.
Improved comfort
Reduced solar heat transmission supports more comfortable patient and staff spaces.
Avoided mechanical cooling
The glazing upgrade avoided a much larger air-conditioning capital cost.
Reduced running-cost exposure
The project improved passive performance without introducing new cooling running costs.
Case study overview
Dortech Maintenance helped Ordsall Surgery improve patient and staff comfort, enhance the appearance of the building and avoid costly mechanical cooling through targeted glazing replacement.
The challenge: summer overheating
Ordsall Surgery was experiencing significant overheating within its patient waiting area and consulting rooms during summer months. The affected areas were predominantly south and south-west facing, meaning they were exposed to high levels of direct and late-afternoon solar gain.
The client had been considering air conditioning. Before committing to mechanical cooling, Dortech reviewed the existing glazing and considered whether the overheating problem could be addressed through the building fabric itself.
Site assessment and retained frames
Following a site visit, Dortech established that the existing window and facade frames were in good condition. This created an opportunity to retain the existing frames and replace only the insulated glass units.
This approach reduced unnecessary material replacement, limited disruption to the surgery, and created a more cost-effective route to improving solar-control performance.
Glass performance improvement
| Performance measure | Existing glazing | Replacement glazing | Improvement |
|---|---|---|---|
| Light transmission | 0.79 / 79% | 0.47 / 47% | Reduced excessive solar brightness |
| g-value / solar factor | 0.63 / 63% | 0.21 / 21% | Major solar heat reduction |
| Approx. centre-pane Ug-value | Assumed older DGU | Approx. 1.0 W/m²K | Improved winter insulation |
Dortech recommended Saint-Gobain COOL-LITE XTREME 50/22 II high-performance solar-control glass. The replacement glass reduced visible light transmission from 79% to 47% and reduced the g-value from 63% to 21%, representing approximately 67% less solar energy transmission.
Reducing the cause, not treating the symptom
Instead of allowing solar heat to enter the building and then using air conditioning to remove it, the upgraded glazing reduced unwanted solar gain at source.
The project covered approximately 92m² of glazing, and the client confirmed that the cost of replacing the glass was less than half the cost of the air-conditioning option being considered.
Indicative energy and avoided cooling benefit
| Benefit | Indicative result |
|---|---|
| Useful heat reduction | Approximately 7,507 kWh per year |
| Avoided gas input | Approximately 8,832 kWh per year |
| Indicative heating-side saving | Approximately £456 per year |
| Theoretical solar heat reduction | Approximately 21,329 kWh per year |
| Avoided cooling electricity demand if AC had been installed | Approximately 1,777 to 4,799 kWh per year |
| Avoided cooling energy cost | Approximately £394 to £1,065 per year |
Result
By replacing the glass rather than installing air conditioning, Dortech Maintenance helped the client reduce solar heat transmission by approximately 67%, improve comfort for patients and staff, avoid significant capital expenditure, and introduce no additional cooling running costs.
The project also improved the thermal performance of the building envelope, supporting better year-round building performance.
Calculation assumptions
| Assumption | Value |
|---|---|
| Glazing area | 92m² |
| Existing glass light transmission | 0.79 / 79% |
| Replacement glass light transmission | 0.47 / 47% |
| Existing glass g-value | 0.63 / 63% |
| Replacement glass g-value | 0.21 / 21% |
| G-value reduction | 0.42 |
| Assumed existing Ug-value | 2.7 W/m²K |
| Assumed replacement Ug-value | 1.0 W/m²K |
| Heating degree days | 2,000 K-days/year |
| Assumed heating efficiency | 85% |
| Assumed gas rate | 5.16p/kWh |
| Assumed electricity rate | 22.19p/kWh |
Disclaimer: This case study is provided for general guidance. Performance data and energy savings are indicative only and actual results will vary depending on building design, occupancy, HVAC systems, operating conditions, weather, maintenance and energy costs.