The parameters and conditions that govern the ventilation requirements in residential buildings under current regulations worldwide are not harmonized. The reduction in energy demand and the increase in the thermal comfort in dwellings are mainly conditioned by these parameters. This article reviews and compares the ventilation flow rates in residential buildings in various countries: the United States of America, Germany, France, the United Kingdom, and Spain. It also compares the requirements of these countries with the requirements of the Passivhaus construction standard, which is recommended by the European Union as an example of nearly zero-energy buildings (nZEB). Furthermore, a model for a dwelling is created using TRNSYS software. First, simulations have been performed with the flow rates, ventilation strategies and envelope transmittance required by the regulations of each country. The cooling and heating demands have been obtained for representative cities in different climate zones. With these results, the impact of ventilation parameters in the heating demand of the proposed Spanish dwelling is analyzed. Secondly, the same dwelling has been simulated with the thermal envelope transmittance values recommended by the Passivhaus standard. The ventilation strategies of each country have been maintained. The influence of the ventilation can be observed uninfluenced by other design parameters. It is found that with the current ventilation strategies, the heating and cooling demand values required by Passivhaus can be reached in only a few warm climates. In other cases, the ventilation strategies will need to change, and heat recovery ventilation will be required.

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The COVID-19 crisis has changed daily habits and the time that people spend at home. It is expected that this change may have environmental implications because of buildings’ heating energy demand. This paper studies the energy and environmental implications, from a Life Cycle Assessment (LCA) approach, due to these new daily habits in residential buildings at their current level of thermal insulation, and in different scenarios of thermal retrofit of their envelope. This study has a building-to-building approach by using Geographical Information Systems (GIS) for the residential housing stock in the case of Barcelona, Spain. The results show that a change in daily habits derived from the pandemic can increase the heating energy consumption and carbon dioxide emission in residential buildings by 182%. Retrofitting all buildings of Barcelona, according to conventional energy renovation instead of nearly Zero Energy Buildings (nZEB), will produce between 2.25 × 107 and 2.57 × 107 tons of carbon dioxide. Retrofitting the building stock using energy recovery is the option with better energy and emission savings, but also is the option with higher payback time for buildings built until 2007. The methodology presented can be applied in any city with sufficient cadastral data, and is considered optimal in the European context, as it goes for calculating the heating energy consumption.