Low-carbon luxe: Hartdene Barns revisit

A couple of years ago I wrote a story about some rather special homes being built on the site of a former dairy farm in Kent.

Well, it’s time for a revisit to Hartdene Barns, to see how the plans that promised so much turned out…

To recap, the disused dairy farm outside the village of Cowden in Kent, near the border with East Sussex, was in a sorry state when it was bought by brothers Damien and Michael Wynne.

The pair are experienced developers, with several up-market developments in south east London under their belts through their Q New Homes company, but this was a big project even for them.

Old dairy farm

The farm had been in the same family for several generations until the last farmer died in 2017.

Over the last years of the 93-year-old former owner’s tenure, the place had fallen into a state of disrepair.

When the brothers took the place on, it was a typical hotchpotch of agricultural buildings of different ages and different purposes: milking parlour, hay barn, cattle shed, dairy and so on.

At that point, planning permission was already in place for a residential scheme that retained ten buildings (nine former agricultural buildings plus the farmhouse) while demolishing some of the smaller, peripheral structures.

Getting rid of the lean-tos and secondary structures enabled the opening up of a central courtyard and views out towards the rolling Weald landscape beyond.

But all the key farm buildings were retained, with the shape of the new dwellings dictated to a large extent by the existing agricultural structures.

A key stipulation of the planning permission was that the new homes would retain the structural frames of the existing farm buildings, so that the houses would echo their previous forms.

Architectural vision

At this stage, top architecture practice Nissen Richards Studio was appointed to refine the architectural vision, and Jim Richards and his team finessed the designs to great effect.

They kept to the proposed building footprints, but created new internal layouts and radically altered the homes’ external appearance to feature charred timber cladding and black zinc roofs, rather than the pale timber originally proposed.

The homes are a mix of three and four-bedroomed properties, with the largest five-bedroomed home measuring 6,500ft², and the new designs give them a thoroughly contemporary appearance outside and in.

An echo of the working farm that had developed ad hoc over decades is retained in the development’s disparate architectural forms, but the rustic structures have been transformed into highly desirable luxury dwellings.

The forms and silhouettes give the development a sense of place and a reminder of its past, but the modern incarnations are wonderful: striking, high spec, luxury eco homes.

Detailing

A variety of cladding patterns has been used across the site to highlight entrances and feature areas.

The variations add tactility and break up the large-scale elevations.

The family of patterns creates a unique design for each dwelling while also unifying the overall scheme.

It includes ship-lapped vertical boarding with varying widths of boards and rectangular boards and alternating vertical fins with open joints.

Large glazing has been used wherever there are large views – out over the beautiful Kent countryside – with smaller windows where the view is towards common areas.

Sustainability

Sustainability lies at the heart of this project.

The Barns have been designed to measure up to the challenging RIBA Climate Challenge 2030 standards.

The Challenge is a voluntary framework created by the Royal Institute of British Architects to help architects design buildings that meet net-zero carbon goals.

It sets tough performance targets for buildings in the following key areas: operational energy use, embodied carbon, potable water use, and health and wellbeing (daylight, air quality, overheating etc).

So, for example, the 2030 targets for homes – the targets the Barns have to meet – include for operational energy <35kWh/m²/year; for embodied carbon <625kg CO₂e/m²; and for potable water <75l /person/day.

Jim Richards explains, “This was the practice’s first ever project to adopt the standards and requirements of the RIBA Climate Challenge, which was an exciting opportunity, but also presented significant challenges we needed to overcome.

“Meeting the potable water use targets was definitely more challenging than anticipated.

“While we met the 2025 target of 105 litres through careful specification of appliances and fittings, we found the 2030 target of 75l was only achievable with rainwater harvesting and site-wide water recycling.

“Future projects will need to incorporate these strategies to reduce potable water consumption.”

The barns are kitted out with a host of green tech, including air source heat pumps, extensive insulation, MVHR systems and electric car charging points.

These are fully electric homes, powered by solar photovoltaics (PV).

High-output black Jinko 440W PV panels blend into the black zinc roofs, while Sigenergy battery systems let residents store and manage their own clean electricity.

The barns were constructed according to fabric-first principles that involved airtight construction, deep insulation and the elimination of cold bridges.

The walls are built using well insulated structural insulated panels (SIPs) that embody much less carbon than traditional masonry walls.

Those bricks that were used on the scheme – Michelmersh Selected Dark stock – were manufactured just 12 miles down the road using traditional methods.

All the properties at Hartdene have a SAP (standard assessment procedure – the testing methodology used to calculate energy performance certificate (EPC) ratings) score of over 100.

That means they should generate at least as much energy as they use: which means ultra-low energy bills.

Interior design

In contrast to the dark exteriors, the property interiors are light, bright and filled with natural tones.

Full-height, glazed Crittall-style doors create a connection between the primary living spaces and entrance hall.

Interior design at the Barns show home was done by Jo Brown of Tile House Studio, who was nominated for two British Institute of Interior Design (BIID) awards for her work at Hartdene.

Local artisans

Jo has used a palette of natural neutrals and emphasised sustainable and reused materials, such as the tables she commissioned from designers Tomas and Jani, which are covered in the unique material Kava that the duo has developed made from coffee grounds.

Another local craftsperson, potter Forest Tozer of Together by Nature, has handmade bespoke ceramics for Hartdene using clay from the site and decorated with plants gathered there.

Sustainability underpins every aspect of the decor.

Engineered oak floors don’t just offer natural beauty, they can be sanded and refinished multiple times.

Carpet was consciously excluded, on the other hand, because, during the project’s whole-life carbon assessment, carpets were identified as unsustainable because they typically need to be replaced up to six times over the life of a home.

Another thing you won’t find in the barns is skirting boards, instead there are clean, minimalist lines with shadow-gap detailing.

Pond

The Barns sit within 37 acres of land. Gardens are sown with wild grass mix.

A pond on the site is now a tranquil haven for wildlife, but it began life in dramatic fashion as a bomb crater, created when a German bomber returning home after a bombing raid on the capital in World War II jettisoned an unused bomb into the Kent countryside to lighten its load on the way home.

Private allotments

Beyond the newly landscaped pond is a unique feature of the scheme: private luxury allotments.

Each house has an allocated organic veg plot, currently tended by experts from Roots Allotments.

Future homeowners can choose whether they want to get involved with the growing, or simply want to receive the fresh produce grown on their patch.

Surrounded by a newly planted orchard, the allotments each have their own cute little potting shed.

The sheds are made from offcuts of the charred timber cladding used on the houses – making sure none went to waste.

The oversized shed roofs harvest rainwater for watering and shelter integrated bench seats that look out over the raised allotment beds to the valley beyond.

Area of Outstanding Natural Beauty

The development sits in the High Weald Area of Outstanding Natural Beauty, and the picturesque landscape surrounding it is typical Wealden country, gently rolling hills with lots of woods.

Despite the rural location, the Barns are well connected. Cowden Station is just three minutes’ drive away, with regular trains into London.

It’s not surprising then that some of the barns have already been sold.

The rest are just on the market.

Last word

Thanks to impeccable detailing, the finished homes are even more striking than I imagined they would be when I first saw the renders and drawings two years ago.

The sharp, black silhouettes express the essence of the old farm, but these sophisticated properties are more than a cut above the average barn conversion – built to the highest aesthetic and environmental standards.

Jim Richards puts it well: “Working with distinctive forms and silhouettes, and meeting challenging sustainability targets, while providing generous and inspiring internal spaces that capture views of the surrounding landscape has been a delicate high-wire act, but the final buildings are all we hoped for.

“They have a sense of place and a notable link to the past, but the modern incarnations of these former agricultural buildings are also built to the highest specification to provide buyers with luxury, low-carbon homes.”