As sustainable construction advances, home design must go beyond energy efficiency, considering daylight, ventilation, comfort, and embodied carbon. Neil Freshwater of VELUX explores how daylight and Indoor Environment Quality can contribute.

In the pursuit of more sustainable and energy-efficient homes, a holistic approach to building design is crucial. While the Future Homes Standard (FHS) and existing Approved Documents provide a regulatory framework for energy efficiency, they fail to consider several critical factors that contribute to overall building performance. 

Among these, daylight provision is a significant omission. Natural light in homes directly influences occupant health, well-being, and energy consumption.

In December 2024, VELUX launched the #DaylightChampion campaign in the UK Parliament, bringing together daylighting experts and politicians to highlight its importance. Additionally, the Parliament’s All-Party Parliamentary Group (APPG) on Healthy Homes & Buildings, whose advisory board we are a member of, has long championed the need for a holistic approach to building policy and design.

The Importance of Daylight in Buildings

Despite its benefits, daylighting remains overlooked in UK building regulations. The current Approved Documents and the proposed Future Homes Standard focus on energy efficiency and ventilation but do not include minimum daylight requirements. This is a missed opportunity to enhance occupant well-being while reducing reliance on artificial lighting.

Roof windows effectively maximise daylight penetration due to their lack of exterior obstruction. Research shows that exposure to natural light improves mental well-being, productivity, and sleep cycles. Homes with adequate daylighting require less artificial lighting, reducing energy consumption and carbon emissions.

The Bigger Picture – Healthy & Holistic Building Design

The VELUX Group has long championed Active House design principles, balancing energy, environment, and indoor comfort. These principles consider environmental impacts like embodied carbon and water efficiency, as well as indoor comfort parameters including thermal comfort, air quality, daylight, and acoustics. These can be objectively measured and incorporated into design specifications. Across the Irish Sea, the Housing Performance Index (HPI), championed by the Irish Green Building Council (IGBC), exemplifies this holistic approach.

Addressing Overheating Concerns

Overheating has become a pressing issue as buildings become more airtight. Part O of the Approved Documents seeks to address this but has had unintended consequences – reducing daylight access due to the simplified calculation method, which limits maximum window areas. Many house builders report difficulties complying.

The government is currently reviewing Part O, offering an opportunity to incorporate strategies such as exterior shading – common in mainland Europe – and stack-effect ventilation, which leverages upward airflow to cool buildings. Additionally, incorporating daylighting requirements would ensure that overheating mitigation measures do not compromise natural lighting.

Part Z? The Call for Legislating Embodied Carbon

Construction accounts for around 40% of global carbon emissions, with about 25% stemming from the manufacture, construction, and disposal of buildings rather than operational energy use. Improving energy efficiency has an environmental cost due to material choices. While necessary, we must also acknowledge the true environmental impact and encourage manufacturers to reduce embodied carbon. The proposed Part Z campaign, which aims to legislate embodied carbon considerations, warrants serious attention from policymakers.

Striking the Right Balance

Buildings are systems, not just collections of components. Holistic design is essential. While building regulations’ Approved Documents have improved, some remain disconnected due to siloed regulatory writing. For example, the Future Homes Standard considers only a fraction of the 19 existing Approved Documents.

As the Future Homes Standard progresses, we must advocate for a balanced approach. Daylighting, ventilation, shading, and embodied carbon must be integrated alongside energy efficiency measures to ensure that new homes are sustainable, comfortable, and environmentally responsible.

Neil Freshwater is public affairs manager at VELUX Great Britain & Ireland