key: cord-0985861-g7n4nd0c authors: Cortiços, Nuno D.; Duarte, Carlos C. title: Energy efficiency in large office buildings post-COVID-19 in Europe's top five economies date: 2022-04-26 journal: Energy Sustain Dev DOI: 10.1016/j.esd.2022.04.006 sha: 000f0b5e90112a45a920b49ae0c0ce27a890d4da doc_id: 985861 cord_uid: g7n4nd0c Since the World Health Organization announced the COVID-19 pandemic, indoor airflows became a synonym for virus super-spreaders and the focus point for the scientific community and professional associations across the globe, disrupting all daily life dimensions. Europe's quick response to control the disease led the REHVA board to address mitigation guidelines, reassessed by each member association's following national specifics. The present study aims to quantify the energy consumption and CO2 emissions of “large office” buildings in top-five European economies under the COVID-19 guidelines under the post-pandemic telework forecast. Methodology resorted to a standard model under Building Energy Simulation assessment to compare prior and posterior scenarios. The latter displays a tendency to increase energy and CO2 emissions in all locations, in the first form 10.18% (Rome) to 69.48% (Paris); and second 5.80% (Rome) and 120.61% (Paris), which will affect national energy production and imports, urban pollution and business competitiveness. On a different scope, future HVAC guidelines need to address the incoming figures, particularly in highly dense urban areas. Also, to comply with the goals set by the Paris Accord. -REHVA (4.1) and WHO (2021) guidelines [3] , [15] . (a) REHVA guideline mentions the -temperature‖ and -relative humidity‖ issues as non-relevant for SARS-COV-2 dissemination. Therefore, the authors adopted the values mentioned by Brelih [16] on REHVA Journal Vol 50/2. Today, company leaders reflect on synergies to reduce running costs while ensuring the workers' comforttelework trends to address both goals while realizing space to ensure workplace health and safety. Auditors of leading companies step up to survey national markets on telework engagement in the post-COVID-19 era. During the pandemic in Europe, the IWG Global Workspace Survey/Survey Snapshot published a report in March 2020, interviewing 15 000 businesspeople across 80 nations about the critical drivers for flexible work. The results show that half of the workforce spends 2.5 labor days in the office; where 85% confirm a rise in productivity has flexibility result; 4/5 confirm readiness to work under a hybrid week; 65% of businesspeople agree in model capacity to reduce logistics costs; 65% of interviewed concluded productive increases in tailored work environment align with workers expectations and needs [17] (see Chart 1 below). 3 Depends on the assessed country, see Appendix A, Table A2 . Chart 1 -Pre-COVID-19 -Assessed countries towards flexible work [17] . On November 23, 2020, the McKinsey Global Institute published a report on hybrid work after the lockdowns concerning 2 000 tasks under 800 jobs in nine countries, including the targeted countries (except Italy. The study concludes that hybrid work will not be universal, somewhat reserved to the highly educated depending on online terminals, favoring (>50%) finance and insurance (US 76-86%), management (US 68-78%), scientific and technical support (62-75%), information technology and telecommunications (US 58-69%), and education (US 33-69%). Overall, it will first reflect on the developed economies followed by the emerging markets [18] (see Chart 2 below). Chart 2 -Post-COVID-19 -Assessed countries for the hybrid work model [18] . Lastly, in August 2020, the Joint Research Centre of the European Commission and Eurofound studied the potential of telework in Europe (excluding the UK) and the risk of digital asymmetries, and delivery similar figures: DE 38%; FR 39%; IT 37%; and SP 34% [19] . As restrictions ease, COVID-19 experiences should tackle the upcoming social development or crisis. Likewise, it guarantees the economy's growth and population's well-being and helps countries comply with international commitments to reduce energy consumption and increase efficiency. The COVID-19 guidelines design paves the road to telework/hybrid work, framing the "new normal," with health and safety in mind [20] . Nevertheless [37] . The hybrid work model will likely become the -new normal,‖ working some days at home and others at the workplace, probably without an individualized station/place. The gathered knowledge will help companies' managers to trust and promote remote work, which releases space to support social distance, safety, and healthy environments for users [38] . Finally, the EU signed and ratified the Paris Accord. The post-COVID-19 lessons inevitable pressures the energy supply; after the drop by (-)4%, in 2020 rose by (+)0,5% (2021 comparing e to 2019 figures) [39] . The knowledge economies like Europe (1%) and the US (0.75%) invested in renewables to compensate for the growing energy demand, but even more in China (1.85%) and India (0.65%) (2021 relative to 2019 levels) [40] . The team assessed the energy performance under a Building Energy Simulation (BES) [41] - [43] on a Building Energy Model (BEM) (see Table 3 and Figure 1 below) to compare the disrupted performance in COVID-19 HVAC operating conditions before (pre-C19) and after (post-C19) the pandemic. The study resorts to cove.tool web-based software [44] . The cove.tool is a LEED-approved energy simulation software with an intuitive interface that has proven to aid field experts in designing strategies targeting energy efficiency in new and existing buildings with more than 10 000 accesses during working hours 5 . According to Forouzandeh et al. [45] study on energy simulation software, cove.tool falls into the Normative Calculation Method category, which estimates energy consumption using the statistical method with an empirical or pre-simulated dataset. Plus, the tool is compliant with the EN 15603 6 and ISO 13790 7 [46] calculation methodologies and proved its reliability at the developers' validation tests, showing a 5% deviation on office buildings compared with the industry benchmark EnergyPlus [47] . The software offers a vast array of outputs per carrier, such as annual energy use intensity (EUI) per field and CO 2 e, which proved to be fundamental for the development and purpose of this study, accordingly with the following steps:  The first step starts by designing the BEM in the Sketchup software with a direct geometry upload link 8 to cove.tool energy simulation software;  Thee second step performs an annual energy simulation in five European cities (Berlin, London, Paris, Rome, and Madrid), which were selected for being the capitals of the European countries with the highest gross domestic product [48] (see Table 2 below);  The fifth and final step happens through the assessment of ten simulations, two for each location, upon the same number of reports for posterior consideration and comparison, describing the EUI on -cooling‖, -heating‖, -lighting‖, -plugs and equipment‖, -pumps‖, -SWH‖, and environmental impact in -CO 2 emissions‖ (see Appendix A, C). A prototype/archetype model is an abstraction that summarizes specific building features (parameters) related to the selected building typology, defined by its shape and geometry, envelope specifications, systems, and usage/schedules. Combining the prototype model with parametric experiments allows to evaluate the energy performance of a specific building type [50] . Kemna report for the European Commission [51] frames the standard EU -large office‖ building archetype geometric features (pp. 52) that serve as the research BEM baseline to simulate a building in operation before the COVID-19 uprising (pre-C19 scenario) and under the guidelines in a posterior period (post-C19 scenario)(see Table 3 and Figure 1 below). The absence of a ratified EU -large office‖ building prototype that covers more than geometric features in the selected countries (except UK in 2013 [50] , and Italy in 2011 [52] ) led the authors to resort to the Pacific Northwest National Laboratory (PNNL) «ANSI/ASHRAE/IES Standard 90.1-2020 -Prototype Building Model Package» [53] , specifically the -Large Office‖ building prototype 10 (see Appendix A) to build the baseline concerning -systems‖ specifications. The envelope specifications (U-values and SHGC) vary according to the national code requirements of each country (see Table 4 below), as well as the -systems‖ inputs (see Table 5 below). The latter follows upgraded data from supplementary sources. [a] The SP Thermal code limits the solar factor to 0.58 for south-oriented glazing covering 20% of the envelope surface [59] (p. 7). Note: National climate zones: Paris zone H1a; Rome zone D, Madrid zone D3. The post-C19 scenario contains a range of measures intended to emulate a building's operation in the post-pandemic era (see Table 6 below) against the baseline pre-C19 as described in Figure 1 , Table 4 , and Table 5 (above). The telework standard served as an effective measure to control the pandemic [6] , [72] , for which its implementation success appears to shape today and future work environments [18] , [19] . In this way, Sostero et al. [19] forecast a telework potential ranging between 34% and 39% in most of the studied countries (DE 38%; FR 39%; IT 37%; and SP 34%); while the Mckinsey report [18] state a 39.5% average for the UK 12 The HVAC system operation guidelines advocate the increase of outdoor airflow, raise of ventilation rates, and limit, or even suppress air recirculation [3] , [4] , [15] , [73] , [74] . The post-C19 scenario simulation considers a mix of natural and mechanical ventilation (24/7 running) and suspends air recirculation and heat recovery mode [3] , [4] , [15] . During unoccupied hours, the guidelines maximize the outdoor air to ensure air dilution under deactivated DCV [74] . Adds a pre-and post-two-hour air-flush schedule 13 on workdays in Berlin, Paris, and Madrid [4] . Also, the outdoor air rate -per person‖ rises to 15 l/s (except Madrid with 12.5 l/s [13] ) and -per area‖ to 2.0 l/s, following REHVA guidelines [3, p. 18 ] (see Appendix A, Table A1 ). With no evidence regarding the virus life cycle and to guarantee indoor thermal comfort for users, RHEVA does not recommend adjusting the temperature and humidity levels [3] , despite other sources stating that higher indoor temperature and relative humidity reduce the virus survivability, while lower figures (e.g., RH < 40%) exhibit the 11 The efficiency value varies according to location. 12 Average value obtained from the -theoretical maximum‖ and -effective potential‖ from the Exhibit 3 [18] . 13 Despite being recommended by WHO and RHEVA guidelines [3] , [15] , [74] only German, French, and Spanish guidelines recommend it at a national level. J o u r n a l P r e -p r o o f opposite effect [75] . For those reasons, the authors kept the pre-C19 indoor conditions for each location unchanged (see Table 5 above). The guidelines recommend installing ultraviolet germicidal irradiation devices (UVGI) as a complementary measure to HVAC tuning. Cavallini et al. highlight the efficiency of this kind of installation when combined with high air renewal rates to diminish the virus spreading and infections odds [76] . REHVA 4.1 guidelines suggest the application of an -upper-room‖ or an -in-duct‖ strategy to disable airborne viruses 14 [3] . Nevertheless, national guidelines push for in-duct in DE and SP, and upper-room and in-duct in UK, while FR and IT do not approach the issue (see Appendix A, Table A2 ). The upper-room UV light enables viruses anhelation in the indoor air near compartments ceiling, while the -in-duct‖ performs similar disinfection but inside HVAC equipment's or components (e.g., AHU's; ducts) [78] , [79] . The upper room installments prove their effectiveness in deactivating the aerosolized SARS-CoV-2 virus by resorting to a UV-C light at 254 nm wavelength. It is suitable for situations where higher ventilation rates seem impossible to achieve [80] . The use of UVGI devices implies an increase in -lighting‖ EUI. According to Riley [84] , in London, UK following the existing lighting schedule. To target the microbial agents that proliferate in HVAC coils surfaces (in-duct systems), the recommended UV-C light irradiance ranges from 50 µW/cm² to 100 µW/cm², or 0.69 W/m 2 (7.5 W/ft 2 ) consumption to meet ASHRAE's 16 requirements [79] , [85] . According to Fencl's benchmark, a 27 000 CFM system (45 873 Another post-C19 measure oversees the filtration system update up to the ePM10/F8 standard or above, following the REHVA guidelines [3] . The authors considered an ePM10 50% (M5) 17 filter baseline in the pre-C19 scenario, upgrading it to an ePM1 70% (F8) 18 under the post-C19 scenario following WHO recommendations [15, p. 11 ]. The 14 Heilingloh et al. recommend the use of portable UV-C devices for nine minutes at a dosage of 1.048 mJ/cm 2 to inactivate the virus on surfaces [77] . The research does not contemplate internal layout or furniture configuration and, therefore, dismiss this recommendation. 15 Finally, according to ASHRAE, the SHW temperature should be set above 60º C to avoid the probability of virus manifestation [14] , which the authors kept unchanged. Table 6 (below) summarizes the actions previously described. The HVAC operation and cleaning guidelines applied to medical facilities have become the new standard for complex buildings under AHU. The focus of those measures falls on safety and health rather than energy consumptionprecisely the knowledge gap that this research intends to address. The BES reliability depends on the BEM quality, which gathers its geometry from other reviewed and published sources in Europe. The -large office‖ standard building formal features follow Kemna's baseline research as a BEM standard [51, pp. 52, Figure 12 ]. The five steps methodology addresses the pandemic mitigation measures under the telework project figures on EUI and CO 2 e levels. Due to the sparse data concerning envelopes, systems, and usage/schedules on EU -large office,‖ except the UK in 2013 [50] and IT in 2011 [52] , and to assure the model reliability, the authors opted for a peer-reviewed model. The The study fulfills the gaps with other valid contributions and exhibits the following limitations:  The Kemna report [51] bounds a 0.2 window-to-wall ratio, not considering the climate particularities or the local architectural style of office buildings;  The limited number of cities;  The software limitations of cove.tool, demanding additional calculations like the energy consumption portion related to air filters pressure drop and UVGI devices;  The study did not follow the contribution of national renewables energy sources;  The lack of an -official‖ RHEVA approved EU building prototype package covering also systems and schedules, despite some national endeavors as followed by the UK and IT;  The standard EU -large office‖ [51] BEM applied in every location does not acknowledge building regionalism features, despite the tendency towards a uniform architecture style present in office buildings;  Some national requirements or guidance lack in the details for the -systems‖ inputs, forcing the use of thirdparty sources, e.g., PNNL-ASHRAE's building prototype;  The forecasted -telework‖ figures follow different studies [18] , [19] , recurring to distinct methodologies and approaches. Nevertheless, the presented figures are fairly supported and similar;  The non-consideration of costs involved in HVAC/AHU upgrades, e.g., filtration and UVGI devices. The following data and its interpretation consider the relative values between pre-and-post-C19 scenarios outcomes. The simulation results show the impact of institutional guidelines on how the post-pandemic scenario affects the annual building energy consumption pattern in all locations (see Table 7 The results reflect the total energy consumption due to -heating‖ EUI weight on the whole: an average of 1.95% for -cooling‖ against 51.50% -heating. However, Rome stands below the average with -heating‖ and -cooling‖ EUI figures accounting for 7.80% and 11.36%, respectively. On the opposite side, Madrid and London stand above the -heating‖ EUI average, reaching 65.96% and 67.70%, respectively, of the total EUI. The CO 2 e depend on countries' energy production mix; therefore, they tend to follow the energy consumption behavior (see Table 9 above): London the highest (+2.54%). The study outcomes reflect an overall energy and CO 2 e increase in standard EU -large office‖ buildings located in The European assessed energy consumption and CO 2 e figures represent a global concern that extends the discussion wherever the context applies: knowledge base societies, safety and health concerns, and COVID-19 guidelines. Despite the overall -health above energy efficiency‖ approach in large indoor spaces, the numbers created a commitment, ensuring energy efficiency measures without compromising workers' health. Nevertheless, the forecasted telework figures could disrupt the global energy stability and environmental goals. The study methodology and approach have the potential to anticipate scenarios in the international sphere. Although, results differ from climate conditions, energy patterns and prices, and HVAC guidelines. The authors underline the WHO's effort (March 22, 2021) to improve and simplify its guideline helping its members to comply with desirable conditions to protect general public safety and health without undervaluing energy efficiency and CO 2 e. The COVID-19 pandemic forced changes in working environments, leading to the most prominent global work experience; the remote work (telework The scientific community, environmental associations, and governments raised concerns about a wave of energy overconsumption due to the HVAC systems COVID-19 mitigation measures enforcement, circumscribed to office buildings/telework and third-party logistics [92] . The study authors looked at the capitals of Europe's top five economies, aiming to understand and quantify the EUI and CO 2 e impact of the guidelines published by international entities and ratified by their national counterparts. The study resorted to a BES methodology [41] - [43] and an EU -large office‖ archetype model [51] to assess pre-and-post-COVID-19 scenarios, where the latter also comprises the telework forecast for each assessed country. aligned with the study results. The balance remains unknown but opens a research opportunity. Ultimately, because every human action impacts the climate, forecasting is needed to perceive the long-term effect. The study authors aim to raise awareness of guidelines design consequences on energy and emissions following the Paris Accord and other commitments. As the COVID-19 disrupter fades out and telework grows, weighted adjustments are needed to address the nowadays issues of safety and health, concerns, energy efficiency, and CO 2 e. -Provide SARS-CoV-2 information to workers and limited ill discrimination; [7] -Actively cleaning and disinfecting surfaces and objects is mandatory; [4] [3] [7] Table A2 -Summary of the assessed countries' guidelines plus ECDC guidelines for each country. -Places occupants at a reasonable distance from openable vents; -UV-C light is seen as a viable solution for air cleaning (upper-room and in-duct). [20] Italy (IT) -Usual maintenance to ensure the nominal flow rate, plus the cleaning and sanitization of filters, humidifiers, and heat exchange coils; -Pushes for switching off the HVAC systems for 10 minutes before maintenance; -Under opening windows ventilation, the doors should remain closed. [17, p. 9] ECDC -Heat recovery bypass deactivation; -Keeps indoor relative humidity value above 40%; -Outdoor air intake in continuous operation; [21] -Reduces the occupancy level from 7 to 25 m 2 /person to decrease airborne contamination probability; [22] -Promotes social distance and avoid direct contact within confined areas; -Shuts down air recirculation; -Increases air flow rate. -Turns off the air recirculation and resorts to maximum outside air allowed by the system; -Shuts down heat recovery; -Adopts filtration devices HEPA, electrostatic, UVGI (UV-C), photocatalysis; -UV-C preferably -in-duct‖. [a] Additional "fans" energy consumption of 1.19 kW/m²yr SPA; 1.41 kW/m²yr FRA; and 1.42 kW/m²yr DEU, due to the 2 hours air flush pre and post occupancy. [b] Additional "fans" energy consumption of 5.95 kW/yr due to filter upgrade (ePM10 to ePM1) in all locations. 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Comment faire fonctionner et utiliser les installations sanitaires et de conditionnement des bâtiments afin d'éviter la propagation du coronavirus (Covid-19) et du virus (SRAS-CoV-2) sur les lieux de travail Associazione Italiana Condizionamento dell`aria, Riscaldamento Refrigerazione (AiCARR), «Protocol for risk reduction of SARS-CoV2-19 diffusion with the aid of existing air conditioning and ventilation systems Acedido: 13 de julho de 2021 AiCARR), «Gli impianti e la diffusione del SARS-CoV2-19 nei luoghi di lavoro». Associazione Italiana Condizionamento dell`aria, Riscaldamento Refrigerazione (AiCARR), fevereiro de 2020. Acedido: 14 de julho de 2021 Associazione Italiana Condizionamento dell`aria, Riscaldamento Refrigerazione (AiCARR), 2020. Acedido: 13 de julho de 2021 «Guía de ATECYR de recomendaciones de operación y mantenimiento de los sistemas de climatización y ventilación para edificios de uso sanitario para la prevención del contagio por COVID-19 USA: cove.tool ANSI/ASHRAE/IES Standard 90.1-2020 -Prototype Building Model Package American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), 2020. Acedido: 18 de março de 2021 The authors acknowledge the Foundation for Science and Technology (FCT -Portugal) for the financial support granted to the research project UIBD/04008/2020, the Research Centre for Architecture, Urbanism and Design of the Lisbon School of Architecture, University of Lisbon (CIAUD), and the cove.tool team for providing an educational version of the software and their readiness in assisting us pursue our research goals. HVACOperationSchd on/off Through 12/31 WD, SummerDesign 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 (Fan Schedule) Sat, WinterDesign 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 SummerDesign 64 64 64 64 64 64 64 64 64 64 64 64 64 64 64 64 64 64 64 64 64 64 64 64 Sat 64 64 64 64 64 64 64 64 64 64 64 64 64 64 64 64 64 64 64 64 64 64 64 64 WinterDesign 64 64 64 64 64 64 64 64 64 64 64 64 64 64 64 64 64 64 64 64 64 64 64 64 Sun, Hol, Other 64 64 64 64 64 64 64 64 64 64 64 64 64 64 64 64 64 64 64 64 64 64 64 64 CLGSETP_DC_SCH Temperat ure Through 12/31 WD 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 (°F) SummerDesign 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 Sat 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 WinterDesign 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 Sun, Hol, Other 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 Cool-Supply-Air-Temp-Sch All 180 180 180 180 180 180 180 180 180 180 180 180 180 180 180 180 180 180 180 180 180 180 180 180 MinOA_Sched fraction Through