Eugenia Maslova, technical & regulatory affairs advisor at VELUX, asks if the right things are being measured as the Future Homes Standard prepares to come into effect
After another summer of heatwaves, and some unusually warm spells this autumn, overheating has once again highlighted a fundamental question for the housebuilding industry: are we designing homes that work and remain comfortable and resilient as the climate continues to change?
For building designers and policymakers, this is becoming a much broader question than solely how we keep homes warm in winter. Rising energy costs, heating bills, and energy security are all connected to how efficiently a home performs, but so are overheating, ventilation, daylight, and indoor air quality.
The challenge is that homes are increasingly expected to do more. They need to use less energy, reduce carbon emissions, stay comfortable in increasingly varied weather, support the health and wellbeing of the people living in them, and respond positively to broader environmental objectives, from biodiversity enhancement to long-term climate adaptation.
This matters because recent data shows that 1 in 3 Europeans are exposed to at least one indoor climate hazard, highlighting the importance of looking beyond individual energy or carbon metrics and considering the quality of the indoor environment as a whole.
Building for the Future Homes Standard starts now
This more holistic building approach is particularly relevant as the industry prepares for the Future Homes Standard, which is intended to improve energy efficiency and reduce operational carbon emissions of new homes in England.
While regulation provides an important framework, it’s only part of the equation. Homes that fail to balance competing performance requirements can create challenges later in the design and construction process, while early decisions can shape energy performance, comfort, ventilation, and adaptability for decades to come.
One of the clearest examples of the need to balance these aspects of building performance is the building envelope, particularly glazed openings.
Windows as part of the energy balance
Windows affect solar gains and overheating risk during summer, heat loss in winter and passive solar gains during the heating season. They provide daylight, enable natural and hybrid ventilation and contribute to occupant wellbeing and comfort.
Yet regulatory discussions often consider these issues separately, even though windows and roof windows influence daylight, ventilation, thermal comfort, and energy performance. A window that provides valuable daylight and passive solar gains in winter may, under certain summer conditions, also influence overheating risk, depending on orientation, shading and ventilation.
A highly insulated building envelope can reduce heating demand but increase the importance of effective ventilation and overheating mitigation. While additional photovoltaic panels can offset operational energy use, they may compete for roof space with roof windows that provide daylight and natural ventilation.
Among Europeans planning to renovate, a third intend to do so to improve energy efficiency, while 33% are motivated by the need to improve or fix functionality, according to the VELUX Future of Home Report. These priorities show that performance cannot be viewed through a single lens: energy efficiency and living-environment quality matter.
The Future Homes Standard framework is also shifting towards U-values based on actual product size, recognising that real products may perform differently depending on their dimensions. The limiting U-value threshold is not an individual target for every window, but an area-weighted average across the relevant category. Smaller windows therefore contribute less to the overall calculation than larger ones, meaning a small window with a higher individual U-value may have only a limited impact on the overall SAP output.
In some cases, several smaller windows placed on adjacent or opposite elevations may provide a better balance than one large opening, helping to limit overheating risk while improving ventilation through cross-flow.
Ventilation, airtightness and summer resilience
Ventilation is another example of why windows are central to whole-building performance.
As designed airtightness is increased, effective ventilation becomes even more critical. Reducing uncontrolled air leakage means fresh air must be provided deliberately. The balance between background ventilation, purge ventilation, mechanical systems and usable openings therefore becomes central to indoor air quality, overheating risk and energy performance.
Approved Document O introduced consideration of overheating resilience in new residential buildings, including the role of ventilation and night cooling. While this helped raise awareness of overheating as a building-performance issue, the effectiveness of the current framework in addressing overheating under real-world conditions continues to be debated. Cooler outdoor air, air movement, and a building’s natural layout can help remove excess heat and reduce reliance on active cooling where conditions allow. The placement of openings, potential for cross-flow ventilation and use of stack effect all influence how effectively a home can purge heat and maintain comfort.
Demand-driven natural and hybrid ventilation strategies can align ventilation rates with conditions such as humidity, carbon dioxide levels, temperature, and occupancy. However, choosing between mechanical and natural ventilation, and designing homes where openings, shading, controls and systems work together effectively, can be challenging unless these interactions are considered from the earliest stages of design.
Design decisions made early
Orientation, window placement, glazing strategy, shading, ventilation pathways and roof design are fundamentally architectural decisions. A building that uses daylight effectively, manages solar gains intelligently, and provides robust ventilation pathways often needs less correction later than one that tries to solve these issues retrospectively with additional technologies.
For housebuilders and design teams, this makes early-stage coordination increasingly important. The question is not simply whether each element meets its individual requirement, but whether the overall design can deliver a comfortable, healthy and resilient home throughout the year, from summer heat to winter cold.
Fabric, renewables and the roof as a shared space
Photovoltaic systems will play a central role in reducing operational carbon emissions, but their integration needs to be considered carefully. Roofs are not only platforms for energy generation. They are the building’s fifth façade: a shared space that can provide daylight, natural ventilation, and opportunities for habitable roof accommodation.
So, if the regulatory or approval pathway becomes too rigid, design teams may be encouraged towards conservative roof designs that favour simple PV layouts because they are easier to justify and approve.
This is particularly important for room-in-roof and habitable loft designs, where roof windows can play a critical role in daylight provision, ventilation and occupant comfort. More attention should be given to integrating these functions rather than treating them as competing priorities.
A future-proof regulatory framework should encourage renewable generation while retaining sufficient flexibility for justified design variation. This need for a longer-term view extends beyond new-build, with renovation-led measures accounting for 75% of total emissions reduction potential.
Towards genuinely holistic design
As demands on the housebuilding industry continue to evolve, so must our thinking about building performance.
The Future Homes Standard is an important step, but we should ultimately judge its success by whether it enables homes to perform well as a whole, rather than simply meeting individual targets. Design teams need the flexibility to respond to these changing demands to deliver the best outcome for both the building and its occupants.
