Site description

The site was located approximately a quarter of a mile west outside a village boundary and particularly visible from the public highway. It contained a small detached three bedroomed bungalow with an attached double garage and paddock. The bungalow was originally built for an agricultural worker working on the surrounding farmland and there was an agricultural tie on the property which prevented the sale of the house on the open market. The property was too small and in need of modernisation and the land too much for an older couple to manage on their own. The agricultural tie was lifted in 1998, and the property was subsequently sold. However, at that time, the precise extent of the residential curtilage remained unclear.

Proposals

Following the recent purchase of the property, the new owners stipulated that the family home must accommodate both teenage children and grandparents due to financial considerations. Our appointment came about after the withdrawal of two previous planning applications by others. The Parish council objected to the previous proposals because the development was of such a size and scale that it would present an unacceptable intrusion in the open countryside and not comply with the policies of the Joint Core Strategy.

From a design perspective it was important for the proposals to be seen as an extension and not a new build house. Accommodation was placed intentionally at the far end of the bungalow to firstly reduce the impact when observed from the highway and secondly to use the natural slope of the land to step the building down. We enhanced the appearance with dark exterior cladding punctuated with areas of glazing to reinforce individuality, variety and add visual interest. A total of four bedrooms were moved to the first floor level thus freeing up much needed space on the ground floor for a larger family orientated kitchen, dining and sitting rooms.

The overall affect would be subtle, yet a contemporary design incorporating environmental sensitivity and energy efficiency measures. The proposals were to be in tune with the campaign 'retrofirst' that promotes the re-use of existing building stock and low carbon retrofit because of the substantial embodied energy savings compared with demolition and rebuild. The retrofit of buildings is an essential part of the effort needed for the UK to achieve net zero carbon by 2050.

We carefully worked alongside the council and the applicant to minimise the impact of the proposals by reducing the scale significantly from previous designs. It was considered prudent to include a change of use of part of the paddock land to residential curtilage with the planning application.

Guidance consulted when approaching the design

• NPPF 2019
• North Northamptonshire Joint Core Strategy
• National Design Guide

Retrofit measures included

• Improved building fabric encompassing greater levels of insulation to minimise heat loss and dependency on heating costs
• Openable windows and external solar shading methods to large areas of glass are designed to regulate the internal environment so as not to depend on environmentally unfriendly air conditioning methods
• Water saving measures to include low flow taps, toilets, and appliances
• Package sewage treatment plant for foul waste
• Rainwater to be harvested for irrigating the garden
• External lighting designed and installed to best practice in respect of glare, light spill, and efficiency

Discoveries that caused the initial design to be revised

Northamptonshire has high levels of Radon gas due to its underlying geology. Radon can enter buildings and affect the health of occupants living in affected areas. Protection measures installed were deemed necessary in accordance with BRE Report (BR211 Radon: guidance on protective measures for new dwellings).

Ground conditions were found to be heavy clay and as such required deeper than normal strip foundation depths.