Amid rising resource depletion and global emissions, the building sector, one of the most resource-intensive domains, has become central to energy and sustainability initiatives. Efforts, particularly through urban densification and envelope refinements, have primarily focused on improving buildings’ energy efficiency and environmental performance. However, recent shifts aim for a more holistic approach that also prioritizes occupant health, prompted by evidence that stringent energy measures can negatively impact indoor environmental quality (IEQ), which, unlike energy performance, is still governed by general guidelines rather than mandatory regulations. This paper first reviews key findings, particularly within the Swiss legislative context, highlighting IEQ risks associated with measures currently supported by building legislation, such as insulation, airtightness, reduced window size and thermal properties, and certain recycled materials. It then examines clinical and institutional studies on the health impacts of poor IEQ, including effects on cardiovascular, immune, cognitive, and other physiological functions. Ultimately, by clarifying the link between energy efficiency strategies and human health, we emphasize the need for refinements in the regulatory framework to balance ecological goals with the provision of healthy indoor environments.