Duffy House


The Duffy House is a replacement dwelling in an Area of Outstanding Natural Beauty with long views over the Surrey Hills. It is also the prototype of an off-site construction design to be known as “Hart House”. 

The house has a mainly private frontage with just a glimpse through the main entrance portico to the landscape beyond. The rear is largely glazed to allow the living spaces to flow from the inside to the expansive outside terrace and balcony, taking advantage of the outstanding views- which the original house all but ignored.  

The external form and materials used are in the spirit of those recommended by the local village design statements including: a steep pitched roof with clay tile covering, red bricks and pre-finished black Thermowood cladding. The overall look is much more contemporary than the design guides envisaged but not wilful.

The Hart House design takes as its starting point the traditional, simple, scalable and repeatable form of the English black oak barn and transforms it into a pleasing, comfortable contemporary home that's able to embrace the best of twenty-first century technology.  

The long-standing appeal of barns as a reference point is that, as framed buildings, they are essentially volumetric rather than cellular which allows scope for the voids, floating staircase, bridge and vaulted spaces within. The chosen frame material here was laminated oak which can be fully expressed inside and out because, with these section sizes, it chars rather than burns through in a fire.  By tying the frame to ground floor L-shaped masonry walls and encapsulating it within a Structural Insulated Panel  (SIP) superstructure, we were able to take out all the racking forces in the frame. This meant we could use traditional oak-pegged slotted and pegged joints in a contemporary laminated material. Ironically it is difficult to use such joints in solid oak, which splits unpredictably - making it difficult to support large areas of glass. We think that some of the best architecture of today has this strong sense of materiality and craft as an integral part of otherwise contemporary spaces

In most British houses the windows are too small and cluttered by framework – often requiring artificial light on all but the sunniest days.  Daylight is not just about quantity but about distribution. Ironically, glass-walled buildings can actually have the unintended consequence of making the internal spaces look dark because our eyes adjust to the much brighter external light. To avoid this you need daylight from multiple directions. Here the central flat slot in the pitched roof has a long frameless roof-light to provide daylight right into the centre of the living spaces  through the voids.  Added to this all the main rooms have daylight from the opposite side to the principal elevation, or from the side.  The windows are all full height with no secondary framing. The effect of this is that daylight penetrates

The aim of this design is to use the best proven means of achieving energy efficiency, avoiding technologies with a high capital cost with insufficient or no guaranteed payback. 

This includes: 

  • extensive use of natural daylight whilst controlling potential over-heating by passive means.  
  • solar pv array  integrated into south-east facing un-shaded roof 
  • solar hot water panels concealed in the central flat roof slot.
  • Heat recovery ventilation. Warm moist air is extracted from the bathrooms and kitchen and the heat transferred to incoming clean dry air into all the main rooms
  • Kingspan SIP Panel construction from a mainstream manufacturer with excellent air-tightness design details and a good  installer
  • underfloor heating  using mainly large format ceramic tiles which enhance heat transfer and also facilitate solar gain into the same layer of screed.  In winter the solar gain into the floor can take over as the primary energy source at certain times. Overheating is controlled by the brise soleil and balcony in summer, when the sun is much higher, and by internal blinds in the winter months. 
  • enclosed wood-burning stove using locally-sourced logs

Hart House has no pretensions to be art, just to be good straightforward architecture, allowing for  refinement and development over time. Let’s remember that a house is not the main act but rather the stage and background to our lives. Our habitation gives it something of our personality but to have an adaptable future it is surely better if the stage can be easily cleared for  different characters  over time.

“Long life, loose fit, low energy ”* still works for us. 

*attributed to Sir Alexander John Gordon 1974 


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