This exciting Passiv Haus retrofit project involved converting a traditional 1950’s detached house in a North London village’s conservation area, into a very large high energy performance modern home.
We were appointed by our clients to work closely with their architect from the initial design stages to completion. Our role was to ensure the vision for the new energy efficient building, with its large landscaped gardens, was fully realised – and with the minimum stress and financial risk to our clients.
When building a highly energy efficient property, it is very important to ensure that you use an experienced build team, and oversee the construction phase very closely. This project involved the contractor tackling lot of technical aspects, and so it needed a wide range of skills. It was important to appoint a team who had experience of building using Structurally Insulated Panels and large glazed panels as well as one who understood the importance of building to get a high level of air-tightness.
The original house was gutted, remodelled and renovated to create a high energy performance building before the new extension was added. The project involved demolishing a separate building containing a granny flat on the site, plus taking down a couple of single storey rooms to the rear of the property. This cleared enough space to build the large new build double-storey extension, which was then linked to the original house. The extension was built using structurally insulated panels (known as SIPs) and the design also included huge structural glazing panels to maximise the light into the house.
CLPM were brought in to manage and oversee the construction phase of the project. Our first action was to carry out a design review, and create an accurate budget to work to. This involves our team checking that the architectural designs, structural engineering drawings and specifications are all sufficiently detailed and consistent across each item. We then use this information to create a cost estimate budget for the project. Estimating the build costs at this early stage helps our clients to check the affordability of their plans and allows them to set a budget for large ticket items such as bathrooms or kitchens.
The next step was to find and appoint a build team. We do this by carrying out a competitive tender. We create the tender briefing packs, agree a shortlist of builders with our clients and then meet with a selection of suitable contractors. Once the returns are received we then analyse them before helping our clients choose, appoint and manage their build team. We do this by drawing up the building contracts and then usually go on to act as the project’s Contract Administrator.
The role of Contract Administrator involves visiting the site to inspect the works are being completed on time, and in line with the designs and to the agreed costs. In complex projects such as this one the frequency of visit tends to be fairly high – usually at least once a week – to enable our project manager to see the works before they are covered up by other structures. For this project we also helped our clients to monitor and control their finances by reporting their spend to budget on a monthly basis.
While the build was extremely complicated, our clients invested wisely upfront in the pre-constriction planning stage and so there were no major problems with the construction works, and the project went quite smoothly. Our client’s new home is not only extremely light and stylish but as it achieves Passiv Haus performance it also has negligible running costs.
CLPM Services used by our client:-
Design Review, Cost Estimating and Budgeting, Tender Management and Analysis, Monthly Cost Reporting. Contract Administration role with main contractor with site inspection.
Retrofitting to Passiv Haus standards (know as EnerPHit) isn’t easy. It’s a very tough standard to achieve as getting the level of thermal and airtightness levels required in an existing building is likely to be more complex and more difficult on site than with a new build.