TECHNICAL VIABILITY ASSESSMENT 

The PLURAL Project

The PLURAL project pioneers advanced, sustainable solutions for the renovation of residential buildings, employing Plug-and-Use (PnU) prefabricated façade kits designed to improve energy efficiency, comfort, and overall environmental performance. Using advanced technologies like the MODEST-LYSIS tool and Building Information Modelling (BIM), the project integrates data from both physical and virtual simulations to optimize PLURAL’s prefabricated systems for future market uptake. PLURAL’s prefabricated kits have been customized for each demo site to address specific architectural and climatic conditions. Preliminary findings suggest that these systems have the potential to deliver significant energy savings. The renovation methods employed in PLURAL’s kits are also designed to achieve near-zero energy building standards (nZEB), highlighting the project’s commitment to minimizing energy consumption and improving the environmental impact.

Prefabricated Active Façade Systems

PLURAL developed three different prefabricated active façade systems for deep renovation of residential buildings without the need of major alteration in the existing façade:

• SmartWall demonstrated at the Greek demonstration building in Voula.
• ConExWall demonstrated at the Czech demonstration building in Kasava.
• Denvelops Comfort demonstrated at the Spanish demonstration building in Terrassa.

Validation of PLURAL Systems

The validation of PLURAL systems has been based on the following “active” indicators:

• Evaluation by the end users at the end of the monitoring period via interviews.
• The results of the monitoring campaign, in conjunction with the results of the virtual buildings performance identify the energetic performance of the PLURAL systems.

Demonstration of PnU Kits

The PLURAL project proposed a demonstration of the PnU kits in 6 demo cases (3 real demo cases and 3 virtual), selected based on their typologies, climatic zones, and socio-economic conditions so that the feasibility of the PLURAL solution all around the European residential market can be explored.

Real Demo Buildings

• A double residential house located in a natural environment in Kašava, Czech Republic.
• A multifamily residential block forming part of a dense urban structure in Terrassa-Barcelona, Spain.
• A shelter for homeless or low waged families, self-standing and located in Voula municipality, Athens, Greece.

Monitoring Campaign

Greek Pilot: Voula, Athens (VVV)

A monitoring campaign evaluates the performance of the VVV demo following the installation of PLURAL PnUs, focusing on the Indoor Environmental Conditions (IEC). The monitoring campaign was designed in accordance with the relevant standards i.e. CEN 15251, ISO 7730, ISO 7726, and ASHRAE 55 to ensure the reliability of data collected.

The monitoring includes - among others - real-time metrics on building environmental parameters that affect thermal comfort (e.g. temperature, humidity, air velocity etc.) and indoor air quality (e.g. CO2 and TVOCs concentration). Moreover, the comparison of the data collected before and after the renovation facilitates the assessment of the effectiveness of the PLURAL renovation under real-scale conditions. The monitoring period was initiated in September 2021.

The monitored thermal zones of each of the two apartments (A1, A2) are depicted in the picture below. The MS (measurement) points correspond to each zone where the multisensors were installed.

The monitored weather data indicate a typical Mediterranean region, showing seasonal variations in temperature, relative humidity, and solar radiation. Temperature during summer period reaches 39 °C, while winter lows are just above 0 °C. Relative humidity varies between 20% and 95%, inversely related to temperature. Solar radiation peaks at about 1100 W/m² in summer and drops to around 200 W/m² in winter, reflecting increased sun exposure in warmer months. These patterns highlight the impact of solar radiation on temperature and its potential thermal gains affecting indoor environmental conditions.

Regarding the energy monitoring, during the pre-renovation period the energy consumption patterns were mainly characterized by the operation or not of the portable heaters, by creating increased consumptions when the portable heaters were in use (in both A1 and A2 apartments).

During the post PLURAL renovation monitoring period, the results that were obtained for the A1 apartment were not indicative of the interventions realized in the building and could not be compared with the pre-renovation results as the apartment was not occupied during many days of the year. On the other hand, the results for the A2 apartment demonstrated a stability in the consumption pattern after the PLURAL installation in both winter and summer periods, thus, eliminating any serious energy consumption peaks observed during the pre-renovation monitoring.

An overall reduction of energy consumption of 11.05% was observed in total for the A2 apartment, after the PLURAL installation.

Overall, monitored indoor thermal comfort environment of both apartments significantly improved after PLURAL renovation by reducing temperature and humidity fluctuations and stabilizing PMV values near neutrality. Air quality parameters remained within acceptable ranges, demonstrating effective ventilation and pollutant control.

Czech Republic: Kasava

The demo building of Kasava has been monitored before the renovation phase for more than one year. The monitoring showed a very high heating consumption of the building (9’000 kWh/a for a single flat) and that some rooms were characterized by thermal discomfort for both, summer and winter. In particular, the measurement showed that the indoor temperature for one bedroom was in average 18 °C during the winter season, while some other rooms were affected by summer overheating with indoor temperature higher than 30 °C. The collected measurement data also showed very high concentration of CO2 in all the main rooms of the building with zones that even exceed levels of 7’000 ppm, i.e. poor IAQ (Indoor Air Quality) values. These poor values are linked to the fact that the ventilation was carried out by manual opening of the windows which was not sufficient to guarantee adequate air quality for the inhabitants.

Shortly before the end of the project phase, the renovation work was finished, and it was thus possible to conduct the monitoring with the ConExWall heating system for several days. The first data have showed promising results. The ConExWall heating system is able to heat the building and seems to be suitable for such cases (i.e., old building, cold climates, low window to wall ratio). The measurements showed that, with an average ambient temperature of 10 °C, the ConExWall was able to increase the indoor temperature of the rooms of approx. 2 to 4 °C/day. The building model, calibrated with the available measurement data, was used to perform annual simulation and evaluate thermal comfort and heating consumption of the building after the renovation.

The simulations indicate that the PLURAL renovation based on the ConExWall system is able to reduce drastically the space heating demand of the building and in the meantime increase the thermal comfort in all the rooms with an indoor temperature of 21-22 °C and relative humidity between 30 % and 60 % during the winter season. A slight overheating in summer, identified for the Kasava Demo, is due to the fact that the building is not equipped with active cooling system, but the ConExWall could be theoretically used also for cooling purposes. Thanks to the installation of the decentralized ventilation units, the IAQ is significantly improved with low level of CO2 concentrations in all the rooms. Relevant results (i.e., heating demand, thermal comfort and IAQ) are summarized in the following table. It can be noted that the PLURAL renovation concept based on the ConExWall is able to improve the living quality for the inhabitants and can considerably decrease the total heating demand of the building. Measurement data and simulation results (calibrated with measurement data) indicate that such a system represents a valuable plug-and-play renovation solution for old buildings characterized by a simple shape, even if located in cold climates.

Evaluation of quantitative KPIs

The overall objectives of the PLURAL project dictate the need to evaluate technical-environmental-economic Key Performance Indicators that justify:

• Reduction of energy consumption: Near zero energy consumption of buildings renovated with PnU kits (reaching U-Values of less than 0.23 W/m2K; Building primary energy consumption will be less than 60 kWh/m2);
• Cost-effective renovation: ca. 58% reduction in renovation costs;
• Fast-track renovation: PLURAL will achieve at least 50% reduction in the time required for deep renovation;
• Environmentally-friendlier deep renovation, aiming at CO2eq emissions 15% less than the current average 0.6 tCO2eq/m2 and 70% material recyclability.

The comparative results from the PLURAL pilot sites in Greece, Spain, and the Czech Republic showcase how each site adapts to different climates and architectural contexts. The data reflects variations in energy performance, environmental impact, comfort, and economic viability.

Energy Demand and Consumption:

The Greek and Czech sites exhibit lower primary energy demand (71.02 kWh/m²/yr in Greece and 70.3 kWh/m²/yr in the Czech Republic) compared to the Spanish site’s notably high 2035.39 kWh/m²/yr. The Renewable Energy Ratio (RER) is significantly lower in Greece (0.38) and higher in the Czech site (0.74), suggesting that the Czech site integrates renewables more effectively. Spain also achieves a relatively high RER of 36%, likely due to the substantial solar energy potential in the region.

Environmental Impact:

The Czech pilot shows a lower non-renewable primary energy use (1605.97 MJ/m²) and CO₂ emissions (88.04 kg CO₂/m²), indicating a lower environmental footprint relative to the Spanish and Greek pilots, where Spain has the highest CO₂ emissions at 302.46 kg CO₂/m². Recyclability rates are highest in Spain (277.10 kg/m²), followed by Greece (186.46 kg/m²), and the Czech Republic (111.90 kg/m²), indicating varied potential for resource recovery in different setups.

Thermal Comfort and Occupant Satisfaction:

Greece achieves a lower annual comfort percentage (4.14% within ideal PMV levels), while the Czech pilot attains 78% of hours within PMV-Class B standards, suggesting better indoor comfort. In Spain, 35.12% of hours are within PMV-Class B, reflecting more comfort limitations due to perhaps higher demand for cooling.

Renovation Time:

Greece and the Czech Republic completed renovations faster, taking approximately 3.2 and 3.1 months, respectively, while the Spanish pilot required 4 months. These figures are totally indicative, considering the bottlenecks incurred during installation and the prototype nature of the systems.

The PLURAL system demonstrates strong adaptability across different climates, with the Czech site showcasing optimal performance in renewable integration, low environmental impact, and comfort in a continental climate. However, in Mediterranean climates, such as Greece and Spain, the system faces challenges related to energy demand and indoor comfort, especially in urban settings. These results suggest that while the PLURAL system is effective, achieving maximum efficiency and occupant satisfaction will require tailored enhancements to address specific climatic and contextual demands.