ORCHARD HOUSE - A sustainable extension/ retrofit in Surrey.

Overlooking Richmond Park to the north and with the A3 in close proximity to the south, Orchard house has a unique setting requiring a unique design solution to maximise the connection to the garden and park beyond and provide privacy and acoustic seperation from the road.  The main living areas are set back behind a courtyard, providing solice and calm from the noisy road .  The front door opens onto the living space, with views to the garden orientating the layout of the space.  The open plan living, dining and kitchen area are in a L shape, with a vaulted roof over the living space and 4m wide northlight.  This configuration allows for daylight into the space without overheating and a connection to the garden and sky.  The heart of the home is a beautifully crafted oak kitchen with stone worktop. Lighting as always is very important and has been integrated throughout to provide contrasting atmospheres throughout the day.  Upstairs is a new office, with glass doors and balcony overlooking the courtyard and green roof.

Sustainability/ Use of renewable systems.

Every effort was made to reuse where possible and the existing slab and walls were kept and have been highly insulated.  Overhead a green roof  adds further insulation and biodiversity. Insulation not only keeps your home warm in winter but also cool in summer.  The type of insulation is important - with wood fibre outperforming the others for summer cooling and keeping the heat out.  See our guide on insulation types and building form.  

The existing cavity walls to the original house have been insulated also and the house is heated by an air source heat pump (ASHP).  We accessed the £7.5K BUS grant to fund the replacement of the boiler with an ASHP.  ASHP's are very efficient.  For one unit of electricity in, you get between 3-4 units of heat out.  They are quiet and can now come with different colour and printed finish to reduce the visual impact of the external unit.  You need an internal hot water tank also. You don't have to have a passivhaus to install an ASHP.  The more insulated the home the better as the ASHP will be more efficient and cheaper to run, but you can install one with some insulation and as over time you as you insulate further the ASHP will become cheaper and more efficient to run.

ASHP's can be  powered by solar panels on your roof.  You can install solar panels and ASHPs under permitted development if outside a conservation area if you comply with certain requirements.  Solar panels work well with a battery (which can be added in phases if needed) so you can store your electricity to use at night when you most need hot water and heat from your ASHP.  A battery can also be used to buy cheaper electricity form the grid at night to use during the day. At Orchard House there are solar panels on the original house flat roof and a tesla power wall battery.

With a well insulated home you need to ensure that there is sufficient ventilation.  If there is space to your ceiling to run ducts inbetween the timber ceiling joists or under these, or you are building a new home or extension you can integrate a mechanical ventilation system to provide fresh air without loosing heat. At Orchard house we installed posi joists to the extension to allow the ducts for the MVHR to run inbetween these and keep the ceiling level high.  

Fresh, conditionner air was particularly important at Orchard house as it was near the A3 and busy red route with buses so having an MVHR system allows you to have frest air but keep  any fumes and noise from the main road out.  There are single room MVHR systems being developed which are a great option for an extension to part of the house.

After a year in operation we will return to see how the systems have performed and how much electricity was used and saved and what impact this had on household bills.