Redefining Passivhaus Living with Intelligent Control

Gresford Architects: Sustainable design from the inside out

The Old Orchard is both the family home and a working expression of Tom and Phoebe Gresford’s architectural values. Tom is the founder of award-winning Gresford Architects, a practice specialising in Passivhaus, retrofit and sustainable design, while Phoebe is an architect in her own right, bringing a complementary design sensibility to the project. Together, they set out not simply to create a comfortable place to live, but a house that reflects their shared belief in architecture that is economical to run and environmentally responsible, as well as being genuinely joyful to live in.

The couple searched for years for a site that offered more than the opportunity to build new. They were looking for somewhere that could be reworked, a site with character, landscape and potential. Old Orchard’s existing garden, long views and quiet Oxfordshire setting provided exactly that, making it ideal for their carefully considered retrofit.

For Gresford Architects, the project became a way to take their low-energy principles beyond theory and into the realities of daily life: children, working from home, changing seasons and long-term running costs. Instead of demolishing and starting again, the couple chose to adapt and extend the original bungalow, reducing embodied carbon while retaining the site’s established relationship with its surroundings.

Designed as a high-performance building, but also as a sequence of flexible, light-filled spaces that support family life, the result is a house that is both expertly designed and deeply personal. In this way, Old Orchard demonstrates how retrofit, sustainability and architectural richness can coexist in a coherent design approach.

How Old Orchard was designed around energy performance

The retrofit strategy began with restraint. The existing ground floor of the bungalow was largely retained, including its footprint and window positions. The only significant change at this level was the replacement of a poorly performing conservatory with a glazed sitting area that is now fully integrated into the building’s thermal structure.

The house is clad in Western Red Cedar, much of it milled from 14 cedar trees that originally stood on the site. This reduced embodied carbon from the exterior transformation while giving the building a coherent exterior and contributing to the building’s thermal upgrade. A new timber-framed first floor was added above, allowing the house to grow without major intervention to the original fabric. Externally, the building was upgraded with continuous insulation and airtightness, eliminating thermal bridges and dramatically improving energy performance. All windows and rooflights are triple-glazed, allowing generous daylight while maintaining thermal stability. On the south and west-facing windows, external blinds manage solar gain, keeping heat out to prevent overheating in summer.

The building fabric performs exceptionally. But performance alone does not guarantee comfort in daily life — this is where intelligent coordination becomes critical. From an early stage, AVINU specified Gira KNX components as the core control interface for the project, aligning technical performance with architectural clarity. Engagement with the Wandsworth (Gira UK) team during the design phase ensured that product selection, finishes and functionality supported both the performance ambitions of the home and the refined interior aesthetic.

Smart Building Technology: Integrating KNX with Passivhaus Performance

Passivhaus buildings are defined by how little energy they need, but achieving that level of performance in daily life depends on how well the building is managed. In a home like Old Orchard, where airtightness, insulation and glazing have already done the heavy lifting, smart control systems can help to ensure those gains are protected and fully realised.

This is where KNX building control becomes a natural partner to Passivhaus design. KNX is an open, building-wide control system that allows lighting, shading, ventilation, heating and energy systems to operate as a co-ordinated system rather than isolated components. In an energy-efficient home, this integration is critical, small inefficiencies like blinds left open, ventilation running unnecessarily, lighting overheating a space, can undermine the stability that Passivhaus relies on.

Old Orchard’s building fabric — airtight, well-insulated, and triple-glazed — creates the ideal conditions for energy efficiency, but maintaining comfort and optimising energy use often requires intelligent control. To achieve this, KNX technology was chosen to coordinate the home’s core functions, including lighting, blinds, windows, and music, allowing the homeowners to manage the house efficiently while preserving its Passivhaus performance.

To achieve this level of integration, the Gira KNX system was developed, installed and programmed by our Smart Buildings Partner AVINU. Working closely with the homeowners, AVINU provided a co-ordinated, intelligent building management system, carefully tailored to both the building’s EnerPHit performance requirements and the realities of family life.

AVINU configured the Gira KNX system to manage the DALI lighting throughout the home, including the internal and external lights. In certain areas, lighting is also controlled by Gira motion sensors, turning lights on when the space is in use and switching them off when empty. Blinds and roof windows are also integrated into KNX, including Velux blinds and windows, allowing them to be opened, closed or adjusted to control solar gain and ventilation when required. This eliminates unnecessary energy use and aligns with the home’s low-energy performance, whilst offering simple management of key functions to ensure internal comfort.

Lighting and blinds can also be operated through a series of pre-set scenes created specifically for the homeowners, with AVINU using the flexibility of KNX to tailor these controls to the family’s daily routines and patterns of use.. Morning and evening modes allow multiple functions to be triggered with a single action, while whole-house settings such as “All Off”, “All Blinds”, and “All Lights” provide a simple solution to managing and reducing energy use across the house at once. Located by the front door, these controls are also an intuitive way to manage the home when coming and going, ensuring lights and systems are never left running unnecessarily.

Music and entertaining are central to family life at Old Orchard, and the intelligent infrastructure was designed to enhance those moments without adding complexity. At Tom’s request, AVINU created a dedicated Breakfast scene for the kitchen-dining area. At the press of a single button, or via the home control app, the lighting adjusts to the family’s preferred levels while his chosen radio station begins playing automatically. This allows lighting, blinds and sound to work together, giving the homeowners a flexible, responsive environment that supports both everyday routines and more relaxed, social moments. Additional hosting scenes allow lighting, shading and multi-room audio to respond cohesively during gatherings, creating atmosphere while maintaining the home’s underlying energy performance.

Inside, the plan is organised around a series of colour palettes inspired by a kimono pattern from Phoebe’s time living in Japan. These palettes define spaces without enclosing them, allowing the interior to feel connected yet distinct. Sliding doors, mezzanine areas and playful features such as the internal slide enable the house to adapt effortlessly to family life, while still meeting the strict performance requirements of an EnerPHit building.

Supporting this carefully considered interior approach, Gira Pushbutton Sensor 3 switches were selected with both functionality and design in mind. Each switch integrates multiple controls into a single interface, allowing lighting, scenes, blinds and automation to be managed from one compact unit. This minimises visual clutter, reinforces the home’s streamlined, minimalist aesthetic, and ensures that technology enhances the living environment rather than dominating it.

With seven finishes available, two were chosen to complement the colour schemes throughout the house: Cream White Glossy for lighter spaces and Anthracite for darker walls and design schemes, maintaining a cohesive aesthetic across the home. The materials reflect a premium, tactile quality: the smooth, reflective Cream White Glossy enhances brightness in lighter areas, while Anthracite provides a subtle, textured contrast that adds depth without distracting from the overall palette.

The combination of thoughtfully selected finishes, refined materials and multi-functional design allows the switches to sit seamlessly within the architecture of each room, supporting both the home’s Passivhaus performance ambitions and its carefully curated interior character.