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In March 2020, the United Kingdom (UK) government ruled that householders must stay home as a response to the COVID-19 outbreak to help flatten the curve of the epidemic and reduce the exponential growth of the virus. Commercial activities, workplaces and schools were obliged to temporarily close in compliance with the government rules. This first and most restrictive lockdown took place from late March to early May 2020 when occupants had to stay in their homes except for very restricted essential activities. Two other lockdowns were introduced in November 2020 and January 2021, alongside with a range of restrictive measures during 2020. This offered an unprecedented opportunity to investigate the impact of a prolonged period of occupancy on household electricity consumption. In this work, the authors compared electricity consumption data collected from 21 energy-efficient houses in Nottingham, UK, during these lockdown periods to the same period in previous year. The findings indicated that the monthly electricity consumption in April 2020, during the strictest lockdown, increased approximately 5% in comparison to the same period in 2019. The daily electricity consumption profile during this lockdown showed earlier and longer peaks in the evenings with the emergence of a new midday peak in comparison to typical daily peaks prior to lockdown. The findings supported the idea that electricity consumption is increased as a result of the proportion of time residents spend in their homes and this corresponded to 17% more in 2020-2021, when restrictive measures were in place.

The ever-increasing energy demand of the residential sector has required the adoption of tighter energy standards, aiming for high energy efficiency in dwellings. In Brazil, 24 million new residential buildings are planned to be delivered by 2022 through social housing programs, which could greatly impact on the country's energy consumption. In an attempt to minimize this impact, the Brazilian Labelling Scheme for Residential Buildings (RTQ-R label) was launched in 2010 as a voluntary standard for the evaluation of housing energy efficiency. The RTQ-R label focuses on building fabric and hot water systems performances, and generates a score based on the building's energy efficiency levels. The Passivhaus standard, developed in Germany, is one of the most stringent standards and is also the fastest growing energy performance standard in the world with more than 30,000 buildings certified to date. It also focuses on building fabric but establishes a maximum energy consumption target. In this work, the authors developed a comparative review of the RTQ-R label and the Passivhaus standard as means to inform a broader debate about building codes in the context of the current calls by governments for increased energy efficiency. The findings highlighted the different nature of the standards' requirements and targets adopted, and the benefits and constraints of both.

Community Energy' refers to people working together to reduce and manage energy use and increase and support local energy generation. It has the potential to support the infrastructural, social and cultural changes needed to reduce the impact of climate change and increase energy security. The core part of communi ty energy initiatives is people; therefore, successful engagement strategies are essential. SCENe (Sustainable Community Energy Networks) was a research and development project focused on community energy application in a real-world setting involving in its first phase 44 new homes built along the banks of Nottingham's River Trent (UK) in 2016.The project team adopted a variety of established and innovative engagement strategies including website and social media channels, an online user engagement platform, a physical community energy hub with an interactive virtual energy model where meetings and workshops were held, and in-home smart voice-controlled and visual technologies. The influence of the project and the effectiveness of the engagement tools to generate behavioural changes were investigated through a survey, workshops and interviews. It was concluded that engagement with SCENe generated awareness regarding energy issues and participation in community energy initiatives.

In Brazil, the delivery of homes for low-inc ome households is dictated by costs rather than performance. Issues such as the impact of climate change, affordability of operational energy use, and lack of energy security are not taken into account, even though they can severely impact the occupants. In this work, the authors evaluated the thermal performance of two affordable houses as-built and after the integration of envelope improvements. A new replicable method to evaluate the cost-effectiveness of these improvements was proposed. The case study houses comprise the most common affordable housing type delivered widely across Brazil and a proposition of a better affordable housing solution, built in Porto Alegre, southern Brazil, integrating passive design strategies to increase thermal comfort. The findings reveal a potential for improving indoor thermal conditions by up to 76% and 73%, respectively, if costs are not a concern, and 40% and 45% with a cost increase of 12% and 9% if a comfort criterion of 20–25 °C was considered. Equations to estimate costs of improvements in affordable housing were developed. The authors concluded that there is a great scope for building envelope optimisation, and that this is still possible without significant impact on budget.

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Airtightness refers to the amount of air leakage through a building's envelope. This uncontrolled exchange of air between inside and outside, either infiltration or exfiltration, may lead to thermal discomfort. Nevertheless, little or no attention has been given to airtightness in some countries including Brazil. In Brazil, a range of different strategies are suitable to achieve thermal comfort depending on the several climatic regions. In those regions where winter conditions are noticeable, such as in São Paulo, airtightness is a key parameter, but it has been historically overlooked. In this work, the authors deployed the innovative Pulse test methodology to determine airtightness levels for the first time in Brazil, in the city of São Paulo. Three representative multifamily residential buildings dating from the 1970's, 1980's and 2000's were measured, and the results' values widely ranged from 1 h -1 to 5.7 h -1 , at 4Pa. Next, dynamic building simulations were conducted using measured and representative airtightness values (converted to infiltration) to understand the contribution of this variable on the thermal comfort. The results suggested that up to 9% improvement in the thermal comfort levels could be achieved by adopting 1 h -1 as maximum infiltration, and up to 14% by adopting 0.5 h -1 .