RENOLIT ALKORPLAN Bright roofing savings and gains calculator
Enter your building's details and discover the potential savings you can achieve by installing the RENOLIT ALKORPLAN Bright reflective membrane instead of a dark membrane. If a PV plant is foreseen, please, check the box, the calculator will calculate the increased performance of the PV plant, as well.
RENOLIT ALKORPLAN Bright savings calculator FAQs
It estimates the potential economic, energy, and CO₂ emission savings you could achieve by installing RENOLIT ALKORPLAN Bright, based on common building’s characteristics.
The RENOLIT ALKORPLAN Bright Roofing calculator provides an estimate based on standard conditions. For a detailed technical assessment tailored to your specific case, we recommend contacting our team.
Yes, you can repeat the process as many times as needed by entering the data for each building separately.
No, the tool is completely free to use and available online.
Assumed physical characteristics
| Parameter | Assumed value | Justification |
| Roof U-value | 0,2 W/m²K | Flat roof with modern insulation, typical value CTE/EU standard |
| Wall U-value | 0,3 W/m²K | Standard residential building envelope |
| Floor U-value | 0,35 W/m²K | Insulated ground floor slab |
| Window U-value | 1,5 W/m²K | Standard low-e double glazing |
| Openings-to-facade ratio | 20 % | Typical residential building with balconies/large windows |
| Internal loads | 17 W/m² | Lighting + appliances, standard residential occupancy |
| Natural ventilation (ACH) | 0,3 ren/hour | Air changes per hour Moderate natural ventilation (ASHRAE residential) |
| Cooling setpoint | 25 ºC | EU residential comfort |
| Cooling COP | 3,0 | Standard residential split air conditioning |
Operating regime
Seasonal air conditioning. The system is only activated when the outdoor temperature exceeds the comfort threshold (typically May–September in temperate Europe, all year round in warm regions). The model’s cdd_factor captures this seasonality: in Helsinki (CDD ≈ 0.06 KKh/year) the system is hardly used; in Athens (CDD ≈ 10 KKh/year) it operates for a significant part of the year.
Air-conditioned floors
The tool calculates the number of floors as round(height / 3 m), limited to [1, 15]. For example:
- Small block 9 m → 3 floors
- Typical building 18 m → 6 floors
- Residential tower 24 m → 8 floors
- High-rise tower 45 m → 15 floors (maximum)
As the roof only directly affects the attic but the effect spreads to the lower floors via the floor slabs, the tool applies a thermal diffusion factor of 2.5 to the absolute savings. This represents that the lower floors receive, on average, approximately 20% of the effect that the attic receives directly.
Bibliographic justification
- Synnefa, A., Santamouris, M. & Akbari, H. (2007). Energy and Buildings 39, 1167-1174. — Cooling load reduction of 18-93% in Mediterranean residential buildings depending on insulation.
- Zinzi, M. & Agnoli, S. (2012). Energy & Buildings 55, 66-76. — Mediterranean residential buildings (Barcelona, Palermo, Cairo): 21-66%.
- EPA (2025). Using Cool Roofs to Reduce Heat Islands. — 11-27% reduction in peak cooling demand in residential buildings with air conditioning.
- Cool Roof Rating Council (CRRC). For Home and Building Owners. — 7–15% reduction in cooling costs in multi-storey residential buildings.
- Saber, H. H. et al. (2020). — 1–3% in cold/temperate climates, 8% potential in temperate climates with good insulation.
Assumed physical characteristics
| Parameter | Assumed value | Justification |
| Roof U-value | 0,4 W/m²K | Standard flat retail roof |
| Wall U-value | 0,5 W/m²K | Standard commercial cladding |
| Floor U-value | 0,4 W/m²K | Insulated floor slab |
| Window U-value | 2,5 W/m²K | Side glazing and skylights |
| Openings-to-facade ratio | 40 % | Shop windows and glazed areas |
| Internal loads | 21,6 W/m² | High-intensity lighting + sales equipment + public occupancy |
| Natural ventilation (ACH) | 0,045 ren/hour | Low, due to controlled enclosed space |
| Cooling setpoint | 24 ºC | Standard commercial comfort |
| Cooling COP | 3,0 | Central commercial HVAC |
Operating regime
Comfort HVAC with extended opening hours (typically 10am–10pm, 7 days a week). The system is activated when the outdoor temperature exceeds the comfort threshold. Air conditioning is continuous during opening hours, not just in response to temperature peaks.
Air-conditioned floors
The tool assumes 1 equivalent air-conditioned floor regardless of height. Physical justification:
- Shopping centres have a single, extensive roof covering the entire retail space.
- The atria and high-ceilinged common areas (typically 8–15 m) vertically interconnect the different floors, mixing air between levels.
- The anchor tenants (hypermarkets, cinemas) are usually single-storey with a direct roof.
- High-flow mechanical ventilation mixes air between floors via a single HVAC circuit.
- Conceptually, it is more akin to an industrial hall than an office building — an extensive flat roof + a single interconnected air-conditioned volume.
Bibliographic justification
- Romeo, C. & Zinzi, M. (2013). Energy and Buildings 67, 647-657. — Shopping mall Sicilia 13-15% reduction in cooling.
- Synnefa, A. & Santamouris, M. (2012). Advances on technical, policy and market aspects of cool roof technology in Europe. — Mediterranean retail centres: 20–30% peak cooling reduction.
- Akbari et al. 1998 (LBNL). Large flat-roof retail buildings. — 7–15% in hot US climates.
- Levinson, R. & Akbari, H. (2010). Potential benefits of cool roofs on commercial buildings. — Standalone retail buildings in California: up to 9% annual cooling.
- Dow Cool Roof Energy Calculator EU. — Large retail buildings in the Mediterranean: 15–20%; Northern EU: 3–7%.
Assumed physical characteristics
| Parameter | Assumed value | Justification |
| Roof U-value | 0,4 W/m²K | Standard flat retail roof |
| Wall U-value | 0,5 W/m²K | Standard commercial cladding |
| Floor U-value | 0,4 W/m²K | Insulated floor slab |
| Window U-value | 2,5 W/m²K | Side glazing and skylights |
| Openings-to-facade ratio | 15 % | Shop windows and glazed areas |
| Internal loads | 44 W/m² | High-intensity lighting + sales equipment + public occupancy |
| Natural ventilation (ACH) | 0,72 ren/hour | Low, due to controlled enclosed space |
| Cooling setpoint | 23 ºC | Standard commercial comfort |
| Cooling COP | 3,0 | Central commercial HVAC |
Operating regime
HVAC operational during hours of use (typically 9 am–10 pm, 6–7 days a week). Intensive operation in summer due to the combination of high internal heat load (active athletes) and solar radiation.
Air-conditioned floors
The tool assumes 1 floor. A typical sports centre is a single volume with a roof covering the entire space.
Bibliographic references
- CIBSE TM46 (2008). Energy Benchmarks for buildings — Sports centres in temperate climates.
- ASHRAE 90.1-2019 Appendix G — Sports facilities.
- Synnefa & Santamouris 2012 — Mediterranean sports facilities cool roof retrofit.
Assumed physical characteristics
| Parameter | Assumed value | Justification |
| Roof U-value | 0,7 W/m²K | Industrial roof with lightweight insulation |
| Wall U-value | 0,8 W/m²K | Prefabricated cladding |
| Floor U-value | 0,75 W/m²K | Industrial floor slab without additional insulation |
| Window U-value | 3,0 W/m²K | Single-glazed windows in specific areas |
| Openings-to-facade ratio | 8 % | Minimum natural lighting |
| Internal loads | 27 W/m² | Lighting + maintenance equipment + scattered occupancy |
| Natural ventilation (ACH) | 0,06 ren/hora | Very low, airtight enclosure |
| Cooling setpoint | 25 ºC | Operator comfort in operational areas |
| Cooling COP | 3,0 | Standard zonal HVAC |
Operating regime
Partial air conditioning limited to office areas, staff rooms and cross-docking areas. The warehouse itself is not fully air-conditioned — only specific areas. The system is activated when the outside temperature exceeds the comfort threshold in those areas.
Air-conditioned floors
1 floor. A logistics warehouse is always a single volume.
Bibliographic references
- CIBSE Guide F (2012) — Warehouses temperate/cool/hot.
- Dow Cool Roof Energy Calculator EU — Warehouses Mediterranean ~15–25%, North EU 3–8%.
- ScienceDirect (2023) — Single-storey warehouses Australia 25–30% peak.
Assumed physical characteristics
| Parameter | Assumed value | Justification |
| Roof U-value | 0,2 W/m²K | High-performance insulation typical of cold storage |
| Wall U-value | 0,2 W/m²K | Thick sandwich panels |
| Floor U-value | 0,4 W/m²K | Floor with frost-proof insulation |
| Window U-value | 1,5 W/m²K | Minimal, only office areas |
| Openings-to-facade ratio | 3 % | Virtually non-existent to prevent heat loss |
| Internal loads | 9 W/m² | Reduced lighting, low occupancy |
| Natural ventilation (ACH) | 0,06 ren/hour | Minimal, airtight enclosure |
| Cooling setpoint | ≈ 0-10 °C | Typical refrigerated product (varies by product) |
| Cooling COP | 2,0 | Industrial low-temperature system, |
| f_solar_to_cooling | 0,045 | Calibrated against Caladero 2021 (CIRCE) |
Operating mode — always-on
24-hour cooling, 365 days a year. The compressors run continuously to maintain the product at a controlled temperature. The model’s cdd_factor is disabled (= 1.0) for this type of facility, reflecting the fact that solar radiation entering through the roof results in a cooling load throughout the year, not just in summer.
Air-conditioned floors
1 floor. Cold stores are always single-storey structures.
Main validation — Caladero 2021
This typology is the only one that has been validated directly against DesignBuilder dynamic simulation. The CIRCE 2021 study simulated a real cold store (Caladero, Zaragoza) in three European climates. The v3 tool reproduces these results within ±20%:
| Location | DesignBuilder (kWh/m²·year) | Tool (kWh/m²·year) | Deviation |
| Zaragoza (ES) | 10,27 | 12,22 | +19 % |
| París (FR) | 8,98 | 8,24 | -8 % |
| Helsinki (FI) | 7,27 | 7,06 | -3 % |
Bibliographic references
- CIRCE (2021). Energy and environmental simulation of RENOLIT ALKORPLAN roofing products: Caladero case study.
- ASHRAE Refrigeration Handbook — Cold storage cool roof energy savings 8-15 % en climas templados.
- Saber, H. H. et al. (2020). Impact of reflective roofs on overall energy savings of whole buildings.
- ORNL-6527 (1989) Section 5 — Continuously cooled buildings.
Assumed physical characteristics
| Parameter | Assumed value | Justification |
| Roof U-value | 0,5 W/m²K | Industrial roof with moderate insulation |
| Wall U-value | 0,7 W/m²K | Prefabricated industrial cladding |
| Floor U-value | 0,6 W/m²K | — |
| Window U-value | 2,0 W/m²K | Industrial skylights |
| Openings-to-facade ratio | 15 % | Moderate natural lighting |
| Internal loads | 85,5 W/m² | Machinery + production processes (high) |
| Natural ventilation (ACH) | 0,21 ren/hour | Renovation due to process requirements |
| Cooling setpoint | 25 ºC | Worker comfort |
| Cooling COP | 2,8 | Slightly lower than comfort levels under intense thermal load |
Operating regime
HVAC during production hours, typically 8–24 hours in plants operating on a 2–3-shift basis. Air conditioning is important in summer due to high internal loads combined with solar radiation.
Air-conditioned plants
1 plant. Industrial buildings are always single-storey structures.
Bibliographic justification
- Akbari, H., LBNL — Large-area roofs with high internal heat loads, typically 5–15% in hot climates.
- CIBSE TM46 (2008) — Industrial buildings benchmarks. • BPIE (2018) — Industrial sector EU energy use.
Assumed physical characteristics
| Parameter | Small DC | Medium DC | Big DC |
| Roof U-value | 0,3 W/m²K | 0,3 W/m²K | 0,3 W/m²K |
| Wall U-value | 0,4 W/m²K | 0,4 W/m²K | 0,4 W/m²K |
| Window U-value | 2,0 W/m²K | 2,0 W/m²K | 2,0 W/m²K |
| Internal IT loads | 416 W/m² | 416 W/m² | 416 W/m² |
| ACH ventilation | 0,12 ren/hour | 0,12 ren/hour | 0,12 ren/hour |
| Plant room setpoint | 23 °C (ASHRAE TC 9.9) | 23 °C | 23 °C |
| Cooling system COP | 3,5 | 3,7 | 4,0 |
| f_solar (calibrado) | 0,030 | 0,035 | 0,040 |
Large data centres operate with a higher COP due to economies of scale, better equipment design and the availability of free cooling. The f_solar coefficients have been calibrated at the lower end of the range published by ASHRAE TC 9.9 and the Uptime Institute, providing a conservative estimate in the absence of specific dynamic simulation.
Operating mode — always-on
24-hour/365-day cooling to dissipate continuous IT heat. The cdd_factor is disabled (= 1.0) for this type for the same reason as in Cold Storage.
Air-conditioned floors
1 floor. Technical rooms are typically single-storey.
Bibliographic justification
- ASHRAE TC 9.9 (2021). Thermal Guidelines for Data Processing Environments.
- Uptime Institute (2023). Global Data Centre Survey — PUE benchmarks.
- Typical industrial PUE: 1.5 (average DC), 1.3 (DC with free cooling), 1.2 (optimised hyperscale DC).