Technical sheet

Reiken II (tweezicht)

Renovation of a historic townhouse with two faces, no rear extensions, and room for water, plants, and animals.

Water and streets converge and tighten; the urban block is entangled, offers some resistance, but eventually gives in. The plot boundaries appear like a shattered mirror: shards, sharp angles, illogical shifts. That’s what the house stands on. It seems to make up for its modest footprint by stretching skyward: five full floors tall. Behind the historic rear façade, what little open space remained had gradually been choked with a series of extensions. As if the battle against the neighbours’ dense construction could only be won by adding more.

Now the opposite is done. If the house is already this large, do you really need those rear additions? Everything beyond the historic rear façade is demolished. Stone, concrete, and timber give way to earth. For the first time since its construction in 1920, the plot is unpaved. A city garden takes shape: a wild refuge for humans, animals, plants, and water. The house itself is organised vertically. Stacked living. A once-closed stairwell is reopened and brought back into use. The kitchen returns to its historical place in the basement. On the bel étage, a dividing wall is removed, and the space now stretches fully from one boundary to the other. Here, too, you can briefly step outside; like the prow of a ship, a small terrace juts forward. Above this: master bedroom, bathroom, children’s rooms. At the top, the stair ends where it always has: beneath the roof. All the heavy timber is exposed, the roof construction sits visibly atop the volume. A few openings pierce the roof: a skylight for night-time cooling; another for views of the Boekentoren; and an internal terrace that captures the evening sun and opens toward the skyline of towers.

Without any rear extensions, the rear façade composes itself freely. The joinery between stairwell and living spaces shifts slightly. Horizontal bands tie the elements together. A blue plinth grounds the structure. Above that, a yellow belt. A white body. A yellow crown. The crown bows outward, forming a necessary box gutter. All other linear elements, window frames, balustrades, are picked out in a complementary pink. The living room windows sit flush with the outer edge of the wall, allowing the interior to make use of the wall’s depth. The hallway windows are set back, so they shade themselves from the summer sun.

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Referentie egypte — Freed from the rear extensions, the façade is shaped purely by its own composition. A warm palette, caressed by sunlight, stands in contrast to the surrounding dullness. Bands mediate between the stairwell windows and those of the living spaces. A plinth, a body, and a crown.

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The rear elevation is more than worthy of the front. A cheerful, expressionist portrait of its era. Like the historic front façade, it follows the same architectural triptych: plinth, body, and crown.

Retrofit: Improving the energy performance of existing buildings and structures by upgrading them with contemporary systems and technologies

A historic townhouse on Papegaaistraat in Ghent. The challenge of radically improving sustainability here is twofold.

First, this is a heritage building in which many decorative elements have been preserved. The house lies in the heart of Ghent, within the buffer zone of a listed urban view (Coupure), under the strict eye of heritage authorities. The front façade is largely intact and highly valuable, and many of the reception rooms still feature mouldings, historic fireplaces, and original floors.

Second, the plot is exceptionally small, only 78m². About 43m² is occupied by the original townhouse. Including the historic rear wing brings it to 48m², but over time, more was added until the site was completely built over. Such a limited footprint adds further complexity, especially for sustainability measures that come with requirements for placement, acoustics, or scale.

Sustainability is the sum of many interwoven elements. It goes far beyond insulation, heat generation and ventilation, encompassing also overheating prevention, rainwater management, the cooling effects of gardens, and in a broader sense, circularity and biodiversity.

Insulation, at its core, begins with minimising the surface area of thermal loss, building as compactly as possible. The plot may be small, but the house is quite large. That allows us to reorganise all functions within the main volume and eliminate the rear extensions to create an urban garden. One immediate benefit is that the building becomes highly compact. It tucks itself neatly between the party walls from front to back, greatly reducing exposed surfaces.

The rear façade is insulated using a colourful, 22cm-thick STO system. But this insulation does more than just insulate: smaller windows are pushed deep into the façade, so they automatically shade themselves in summer. Larger windows are brought forward and fitted with blinds. The façade is topped with a curved plaster cornice. Aesthetically refined, but also designed to ease the transition to roof insulation.

The roof insulation is a special case. The original timber structure is beautifully intact on the inside. And the headroom near the top landing is limited. These two factors led to the choice for a sarking roof. Insulating over the rafters instead of between them. This way, the entire timber structure, including the boarding, remains visible from within, and the interior height stays unchanged. But not just any sarking roof: most use rigid materials like PUR, which perform poorly against heat and are acoustically inferior. In this noisy street, PUR would amplify tram noise. Instead, we opted for rigid wood wool boards, dowelled into place, with an extra-wide batten at the solar panels to prevent wind uplift.

The high-performance insulation and the newly compacted volume made it possible to install a heat pump without needing to oversize it. This led to the next question: where do you place the external unit? A tiny city garden in a dense block is not ideal. So an internal terrace was carved out of the roof volume. It offers a stunning view over the Coupure and Ghent’s old city centre and also discreetly houses the outdoor unit, free of disturbance. The heat pump feeds fan coil units in all rooms. Underfloor, wall, or ceiling heating wasn’t an option due to the historical finishes. In some cases, creativity was needed to integrate the fan coils as compactly as possible, hidden inside kitchen cabinets, for example.

Managing cold is one thing; heat, another. The heat pump (and thus the fan coils) provides both heating and cooling. Active cooling is a comfort, but it does use energy. The design prioritises keeping heat out in the first place, and makes smart use of night cooling. The staircase acts as a chimney for fresh night air, by opening a window below and the rooflight above. Simple, but it works. City heat lingers longer than in rural areas, but even compact gardens have now proven cooling effects. In this project, the garden, made possible by the building’s new compact form, plays a key role in regulating the home’s climate. Only when passive measures no longer suffice is the active cooling brought into play.

A heat pump is sustainable, but it still uses electricity. Even though roof area was scarce, and rooflights were required on the south side for views, we still managed to install 10 solar panels. The south-facing roof became a compact puzzle of rooflights, solar panels, and service penetrations. A home battery was also installed, decoupling production from consumption.

Water is another crucial theme. Climate change pushes towards extremes: too much or too little. On a plot this tight, water management poses challenges. The story begins with unpaving. At the start, the site was 100% hard surface; no rainwater was absorbed or reused. By moving all living functions into the main volume, demolishing the rear extensions, and creating a garden, we have now unpaved 35% of the site. Rainwater from the main roof is directed either to a restored underground cistern in the garden, or to a surface tank on the roof terrace. Unexpectedly, a five-metre-deep groundwater well was discovered in the garden. In the spirit of frugality, this is connected only to an outdoor tap: used for irrigation, any excess water simply returns to the aquifer. To prepare for the future, the plumbing of the entire house has been laid out to allow for future greywater reuse. A system can later be plugged in to filter lightly contaminated water for local reuse.

Circularity was also (to a limited extent) a part of the project. Wherever possible, dry joints were used instead of wet ones, allowing for future disassembly. Many elements were reused. Sometimes elsewhere in the house, sometimes after restoration.

Finally, the garden brings a real boost in biodiversity. It has been planted with a wide range of native species. A small pond in dappled shade (without fish, and thus no need for filter or pump) attracts dragonflies and, potentially, frogs. There are feeding stations and nesting boxes. A bee hotel and a shelter for butterflies.

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Zie ook project Reiken, Reiken III of Reiken IV (Babylon)