Project name: House, Honeybrook Road
Location: Balham London

This terrace house had remained empty for over two years and was in need of a complete renovation. Our clients wanted a beautiful home with the best potential energy performance for a period property.

The property was extended on ground floor to increase the kitchen and dining room area, maximize the overall building potential within the current Local Authority planning constraints.

The attic space was extended under permitted development to create a master bedroom with dressing room and en-suite bathroom.

The palette of materials is a warm combination of natural finishes, textures and beautiful colours that combine to create a tranquil and welcoming living environment.

We followed a pragmatic and methodical process to help minimise energy usage, including:

• Properly insulating the whole house.
• Ensure low air permeability through natural ventilation to minimise heat loss.
• Decommission the gas supply to reduce carbon emissions.
• Install an air source heat pump (ASHP) on the roof in line with current government advice and Microgeneration Certification Scheme recommendations.
• Install underfloor heating throughout the house to maximise ASHP efficiency.
• Install a Mechanical Heat Recovery System in the basement.
• Ensure all lighting and electrical appliances are as energy efficient as possible whilst still providing a warm and welcoming artificial lighting layout.


Project name: House, Honeybrook Road
Location: Balham London


In order to create the open plan layout on ground floor a series of steel portal frames need to be installed to support all the existing walls and floors
Depending on the loading and the span of the structure the steels need to vary in size

For the rear garden elevation the point loads of the cloumns are such that a re-enforced concrete spreader foundation had to be built to distribute the load along the whole length
The front to back structure along the longitudinal kitchen wall was helped with two small columns. These reduce the span of the steel and help keep the steel sizes to more manageable pieces

The opening to the main building rear elevation is distributed between three columns
The loads are quite high, hence the large middle column

The spine wall also required a re-enforced spreader beam to distribute the load

The open plan attic extension is achieved with a steel ridge beam supported on three story column to the South side. Steels to the North side are supported on new concrete padstones cast directly into the existing party wall

Front to back steels support the chimney stacks at high level allowing for the chimney breasts to be removed on both ground and first floor


Project name: House, Honeybrook Road
Location: Balham London

High insulation and air tightness

In order to minimize energy, use we first need to reduce the heat loss of the building and reduce air permeability
For this we need to determine what standard and benchmark to use for the whole house

Building control sets the minimum standard that should be achieved.
Part L of the Building control regulations sets out the minimum standards for the different elements of the building fabric.
The appointed building inspector will regularly inspect the works during the construction to ensure these standards are achieved

Best practice on the other hand can be taken from the standards set by Passive Haus amongst others

So, for example, external wall construction, Part L sets the minimum standard for new building fabric elements a minimum U-value of 0.26 W/(m2K)
Passive Haus recommends a value of 0.1 W/(m2K)

A solid masonry wall, one brick thick, achieves a basic U-value of 2.0 W/(m2K)
In order to achieve minimum standards, we would need add 100mm of insulation
To achieve Passive Haus standard, we need to add 300mm of insulation

So, in order to achieve a realistic approach, you need to consider the house as a whole and set a realistic target both in terms on material, design implications and budget

Efficient air tightness is achieved by careful detailing of standard building fabric build ups and crucially the interface and detail between the different elements of the building


Project name: House, Honeybrook Road
Location: Balham London

Air Source Heat Pump (ASHP)

In order to de-carbonize our energy consumption we need to move away from fossil fuels and reduce our dependence on gas.
The current direction is to go electric for both heating and hot water.

The ASHP offers a very good Coefficient of Production (CoP)
Declared values by manufacturers are between 3 and 5. This means that for unit of electricity used we obtain three to five units of heating energy depending on the seasonal conditions.

The important factor about ASHP is that it is more efficient at lower temperature levels
This means that under floor heating will be more cost effective than traditional radiators.

A combination of radiators and under floor heating is of course possible but the system will not be as efficient

In this case the ASHP was installed on the roof.
In most cases the ASHP can be installed under Permitted Development (PD) rights.
Installation should comply with MCS 020, Microgeneration Installation Standard

Link to Website:


Project name: House, Honeybrook Road
Location: Balham London

Mechanical Ventilated Heat Recovery (MVHR)

The next step in maximizing heating efficiency and minimizing energy use is to avoid wasting all the warm air by simply opening the windows and loosing al the heat

An MVHR system uses a heat plate exchange to take out the energy from the stail air we want to get rid of and transfer the heat into the fresh air supply to the property

Integrating a full ducted supply and extract system into an existing property is quite a challenge. In this property we installed the MVHR plant in the basement. The natural fresh air supply is ducted from the roof, the stail air is extracted at low street level.
Warm fresh air ventilation is provided to all rooms. Extraction is done from all bathrooms and kitchen.
There is an option to provide background cooling through the system with an additional component.

Cross ventilation is required between bedrooms, bathrooms and common areas. Special fire resistant acoustic baffles were installed to ensure ventilation is provided without acoustic compromise.


Project name: House, Honeybrook Road
Location: Balham London

All combined together

So, the finished product is quite a complex overlay of different elements doing very different things

As with everything the devil is in the detail. It is only by doing a complete refurbishment and stripping out the interiors that a complex ducting arrangement can be achieved.
In order to conceal all the services including ducts, risers and manifolds paths have to be found and hidden in the building fabric.

The result is successful in integrating modern sustainable principles within a period property. Most importantly though creating a modern and elegant home respectful of the building’s heritage.

The client is very happy with the outcome of the project

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