4 Top tips for sustainably extending a Victorian terrace
Sustainability and ecology are at the core of what we do. We are committed to creating spaces using natural, sustainable materials; while utilising low-carbon strategies to heat and cool. Our latest project in South London, the Eucalyptus House, demonstrates how we contribute to Net Zero - both in terms of the building’s embodied carbon, and its operational carbon footprint.
We have summarised some of the lessons learnt from this project, and, together with our longstanding expertise in the field of building conservation, we have put together this list of our 4 top tips for sustainably extending your Victorian terrace.
1/ Installing photovoltaic panels on the roof
We recently received planning permission from Lambeth Council to fit photovoltaic panels (PVs) on the roof of our Eucalyptus House project in the Trinity Gardens Conservation Area. The PV panels will reduce the operational carbon (and energy bills) of this residential property once completed. PV panels are not permitted development in all councils, so this is where the role of an architect is crucial. In this case, the PV panels are discretely positioned behind the tall parapet wall at the front of the house which conceals the original butterfly roof.
For our Eucalyptus House, we are fitting three panels on the south-east slope. The payback period was calculated at 11.7 years, making the initial investment worth while as the panels will still under warranty after this time. The panels are fitted with a battery, which will be installed in the loft space.
Restrictions such as rooflights and chimneys can impact the position and size of the PV panels you can fit, so planning in advance is always advisable.
Figure 1: Our Eucalyptus House in South London, where PV panels will be installed on the south-eastern slope of the existing butterfly roof, hidden from view in the Conservation Area by the front parapet. Image credit: 4 S Architecture.
2/ Improving the thermal envelope
In the case of our Eucalyptus House, thermal improvements to the existing solid masonry walls were achieved by using breathable wood fibre insulation and lime plaster. In turn, this was finished with breathable mineral paint.
Figure 2: Salvaged Victorian floorboards came from a house less than 3 miles away in South London, that our contractor was also working on. Image credit: 4 S Architecture.
Figure 3: The existing solid brick external walls shown here are being insulated with breathable wood fibre insulation. Rockwool acoustic insulation is being fitted between floorboards before new salvaged floorboards go down. Image credit: 4 S Architecture.
3/ Reusing locally sourced building materials
In the existing rooms in our Eucalyptus house, many the existing floor boards were cracked, split and many had been replaced with newer boards. To improve the floor condition and occupant comfort, we specified salvaged Victorian floorboards be used to replace damaged boards where required. Through collaboration with the contractor, we were able to source these locally from a project in East Dulwich that the contractor was also working on where they were being removed. This minimised waste, while ensuring that carbon transport miles were negligible - the floorboards only needed to be transported less than 3 miles!
To achieve this, we ensure that we always maintain open channels of communication with our clients and contractors to look for these sorts of opportunities.
4/ Specifying double-glazed heritage windows
Our Eucalyptus House is nestled down a mews in the Trinity Gardens Conservation Area, so care needed to be taken when replacing the single glazed windows with double-glazed, heritage windows. Mullion arrangement, sash horns, and frame detailing needed to carefully match the existing windows as closely as possible. Note that in some Conservation Areas and with Listed properties, existing window replacement might not be permitted, so it is always best to speak with a RIBA accredited Conservation Architect first and ensure permission is secured with the Council.
Figure 4: Mullion arrangement, sash horns, and frame detailing have been carefully matched to the existing windows with these replacement double glazed units. Image credit: 4 S Architecture.
When replacing windows, it is also important to ensure that the wall is insulated as well. If it isn’t already, this change should ideally be implemented at the same time to ensure window frames and architraves can be adjusted to suit the increased wall thickness. Failure to insulate the walls will only mean a partial solution - it would be akin to wearing a warm hat in winter, but no coat - heat loss would continue to occur through the wall which typically makes up the majority of the surface area of a façade.
Of course, these are only “4 Top Tips” - there are many other steps one can take to ensure a sustainable renovation to a Victorian terrace, depending on budget, listing status, and the existing condition of the building.
As the Eucalyptus House project approaches completion, keep your eyes on this journal. We will be publishing images of the final product in due course. In the meantime, do contact us if you would like to work with us on your sustainably built dream home.