Marie-Claude Dubois

As urban areas grow and face climate-related challenges, rooftop greenhouses (RTGs) offer a promising approach for Controlled Environment Agriculture (CEA) to enhance urban food production while providing potential energy-saving benefits. However, the energy performance of RTGs integrated with mid-rise residential buildings, which represent a substantial proportion of the existing urban housing stock in cold climates, remains poorly understood. This study investigated the influence of RTG integration on the energy demand and indoor thermal conditions of a four-story residential building across cold-climate regions. Dynamic simulations using IDA-ICE were performed to analyze the influence of different glazing and shading configurations, comparing rooftop and ground-based greenhouse scenarios and host building performance. RTG integration reduced the host building’s annual heating demand by 6.2–7.6%, with thermal buffering primarily benefiting the top floor, where heating demand decreased by up to 24.2%, while lower floors remained largely unaffected. No summertime overheating risks were observed. Compared to a ground-based greenhouse, the RTG had a lower heating energy use by 2.8–14.6% depending on glazing and shading configuration, by using free heat from the host building. This study highlights the potential of RTG integration as a passive energy-saving measure, while supporting sustainable urban food production, contributing to more sustainable and climate-resilient cities.

Illumination of dairy barns impacts animal health, milk production, and building energy efficiency. The aim of this study was to assess the existing daylighting and electric lighting conditions of dairy barns located in Southern Sweden. The study specifically examined how different architectural features impact the lighting environment, aiming to identify retrofit potentials in older barns and areas of improvement for new constructions. Ten dairy barns on seven farms were selected as case studies with different construction types, construction year, and size; and were monitored during November 2023 and February 2024. Photometric and geometric measurements were collected, and simulation models were created and calibrated by comparing them with the measurements. The simulation results were used to analyse the lighting performance of the barns. The results indicate that several older barns have lower than recommended illumination from daylighting and electric lighting systems, inappropriate choice of building materials with low reflectance, poor maintenance of building surfaces, etc; thus, requiring maintenance and retrofit measures. Newer barns often showcased improved lighting conditions compared to older barns, primarily due to better daylighting through side openings and skylights (aperture-to-floor ratio: 1-6 % in older barns and 12-20 % in newer designs), underscoring the importance of improving design practices. Older barns consistently showed mean daylight factor values below 1 %, while newer barns exhibited notably improved daylighting. Compared to most older barns having a daylight autonomy below 10 %, newer barns achieved a daylight autonomy higher than 50 %. Mean electric lighting illuminance ranged from 57 to 157 lux across the studied barns. Both new constructions and retrofit projects can benefit from implementing clearly defined design guidelines and lighting requirements for agricultural buildings. Future studies on long-term impacts of illumination on farm animals and human caretakers, environmental and economic assessment of improved barn design and retrofit measures can provide more information on this topic.

Focusing on subjective evaluations of daylight conditions, the present paper explores the relation between room geometric characteristics and perceived brightness and daylight distribution in residential spaces. The study was conducted in 35 apartments consisting of 105 different rooms in the city of Malmö, and selected with respect to typical Swedish architectural building typologies. Questionnaires were distributed by mail to participants, and apartments were surveyed to deduct key geometric characteristics. Results include a reliability analysis of the utilized questionnaire and a correlation study that showed the prevalence of both window size and number as key factors relating to perceived daylight conditions.

Atria are implemented in buildings to increase daylight, foster interaction and provide ventilation. However, their implementation can be complex if good daylight is to be achieved. This research proposed an investigation about the atrium parameters that affect daylight conditions in a case study. This evaluation concentrated in the atrium geometry and the wall reflectance values. Overall, the outcomes demonstrated that shifting the atrium from an enclosed to a semi-enclosed one can double the daylight in the atrium adjacent rooms. Moreover, it is possible to achieve better daylight in the adjacent rooms by keeping the same floor area of the building.