Heion House | Studio Hagen Hall | Media - Sustainability

Embodied carbon

Efficient

Sustainability information provided by Louis Hagen Hall, Director, Studio Hagen Hall.

Embodied carbon overview

A guiding principle throughout Heion House was to remove as little from the existing building as possible and work with what was already there. This extended to how the structure was handled. Studio Hagen Hall worked within existing openings wherever possible and made only one significant structural alteration, widening an opening to accommodate the sliding doors to the courtyard.
Every other change was kept within existing structural supports, allowing the project to avoid introducing additional steelwork entirely. The practice also made a deliberate choice not to extend. Building less but better felt like the more honest response to the brief and shaped the design approach that followed.
Where new materials were introduced, Studio Hagen Hall leaned towards raw, low-process options with a lighter footprint.

Operational Emissions / Energy

Efficient

Operational emissions overview

There were constraints on the renewables side. Listed buildings within conservation areas present challenges. The particular character of Heion House, both in terms of its setting and typology, meant that a heat pump or solar panels were not viable options.
As a result, the project’s efforts around carbon were concentrated on improving the building fabric as much as possible, a constraint that helped focus the approach.

Glazing

The project specifies Histoglass MONO RT+ single glazing in a hand-drawn format, which replicates the characteristic imperfect reflection of older single glazing found in Georgian properties. The glass was also toughened for safety reasons.
MONO RT+ offers a Ug-value of 3.5, compared with approximately 6 for standard single glazing. This represents an improvement in thermal performance while preserving the visual qualities of the original glass.
Even the slimmest double-glazing units could not be considered for physical reasons. MONO RT+ is only 4mm thick, allowing it to fit within the rebates of the original listed window frames and mullions. It was the only product that could meet both the heritage requirements and improve on the thermal performance of what was there before.

Afterlife

Adaptive Reuse and Flexible Design Considerations

Working within the existing footprint meant thinking carefully about sequencing: how the spaces relate to one another, how movement through the house feels, and how usability and connectivity could be maximised without adding floor area.
This included finding ways to activate previously underused spaces. The dining area, for example, had been a low-ceilinged laundry and storage room. By lowering the floor level slightly, Studio Hagen Hall created a sunken dining space and relocated the laundry to a small unused area tucked beneath the front steps. A redundant coal vault was also waterproofed and converted into more meaningful storage.
This constraint became generative. Rather than opening the house up wholesale, the studio created moments of connection between rooms through apertures and screens, an approach that became central to the architectural language of the project.
In terms of the fabric itself, very few new openings were made. One rear window was lowered to form a doorway and an existing opening to the courtyard was enlarged to accommodate the sliding timber doors. Internally, new openings were small and considered.
The majority of the work to the existing building centred on repair and restoration, treating it as the listed heritage asset it is, before carefully inserting new interventions within that fabric. These interventions are physically light touch, although designed to feel as though they belong.
Reversibility was central from the outset and was largely driven by the building’s listed status. Studio Hagen Hall’s interventions needed to be genuinely light touch, without compromising elements that the heritage team considered to be of historic significance.
The original fabric was repaired and restored throughout, including the lath and plaster ceilings and walls, skirting boards, architraves, shutters, and staircase. The new elements sit within that existing fabric so that, if they were ever removed, the heritage elements would remain completely intact.
Adaptability was also important to the spatial planning. The house was reconfigured from three bedrooms to one, but both the top-floor studio and the lower-ground-floor living area were designed so they could be converted back into bedrooms with very little intervention if the needs of the occupants changed over time.

Disassemblable Elements for Circular Economy

On the materials side, the new elements introduced to the house, including timber, porcelain, glass, and stainless steel, are highly recyclable and sit comfortably within circular economy principles.

Sustainability Report

Embodied carbon

Operational Emissions / Energy

Afterlife

Key products in low carbon design