Installed Measures:
Insulation, to existing cavities and roof, and to new extension.
Insulation detailed to provide continuous envelope and avoid thermal
bridging.
Infiltration, all external joinery replaced with Velfac triple glazed
windows, fitted as per the manufacturers details. Sealed cavity vents to
inside. Cut back brick returns at jambs of openings and in-situ concrete
sills where possible, to minimise thermal bridging.
Orientation of glazing, additional and enlarged openings to East and
West, roof lights to flat roof on North East side of the original house
providing high lighting levels and direct solar gain for significant
periods of the day and year, (a net gain).
Heating, Air Source Heat Pump, fully weather compensating controls
and wireless room thermostats, controlling radiant wall panels and
under floor heating.
Cooking, electric only, conduction hobs.
Lighting, all LED.
Appliances, all ‘A+’ rated.
Energy, solar PV on roof, and imported from Good Energy,
(Guaranteed of Renewable Origin, mostly wind power).
Motivations:
It’s important to us that our home is comfortable, secure, and attractive, and we also want it to be energy efficient so that it costs less to run and we do our bit toward saving the planet. So we thought a lot about what standard to aim for and what we could afford.
The first questions were, ‘how much energy do we need to save, and how much will it cost us’? Retrofitting an existing house to meet the highest energy standards can cost a lot of money, and if we think about energy consumption across the whole of our lifestyle there are other ways we could make big savings that might cost less to achieve. The average house would be about 30% of our Carbon Footprint. Getting down to a Passive House standard might typically cost £130-150,000 for an ordinary 3-4 bed terrace house. We could go vegetarian tomorrow and knock 25% off at much less cost. We could also grow more food ourselves, buy our food more locally, walk or cycle to work, and stop flying to far away places on holiday.
Most of these we would try and do anyway, but not everyone wants to become a vegetarian or is able to walk to work. The quick answer is to save as much energy as we can on the house so that we don’t have to be so perfect in other areas.
We aimed for the AECB Silver Standard which is about a 70% reduction on the 1995 Building Regulations, with one important difference, we allow ourselves to count imported energy as zero Carbon because it comes from 100% renewable sources, our PV panels and Good Energy.
Property Background
51 Clive Place is an existing two storey detached dwelling built in 1947-8 as one of a pair of houses by a local Quantity Surveyor. Both are brick, with tiled pyramid roofs, a garage and workshops to the North East side and a terrace to the South West side. They are both of an unusual construction, possibly due to the materials shortages in the immediate post-war period, with cavity walls using larger than usual bricks and mortar joints and a 75mm cavity minimal amounts of timber with the smallest sections possible, a suspended reinforced concrete first floor and, (originally) single glazed steel windows.
The house badly needed some money spending on it. The gas boiler was very old and inefficient, as were the clock timer controls, the micro bore distribution pipes, and single panel radiators. The old aluminium double glazed window units had all failed and were incredibly leaky, and there were air bricks everywhere open to the cavity, which had no insulation. Heating the place must have cost a fortune and produced huge clouds of CO2.
Key changes made
As I said before the house was in relatively poor condition. What it did have going for it was the orientation toward the South. It was also structurally sound and thermally massive, with pre-cast concrete slabs forming the first floor.
We decided to replace all the external doors and windows with very well sealed and fitted triple glazed units, to insulate the cavity walls and the attic, install an Air Source Heat Pump, Solar PV panels, panel wall heating in the existing house and under floor heating in the extension, with fully weather compensating controls, and wireless room thermostats in most rooms. The house had to be rewired and re-plumbed, with a new kitchen, bathroom, utility room, and toilet, and of course redecorated throughout.
We also wanted to make the house bigger. The new extension was built with super-insulated timber walls, and roof lights positioned to collect heat and energy from the sun as well as providing very high levels of day light to the centre of the house.
All the changes were thermally modelled in a programme called Ecotect which made it possible to look closely at several options for improvements and the cost effectiveness of each option.
We had to reduce the heat loss first. Cutting out all the draughts made the biggest difference, then insulating the house as best we could, (using 100% grants for the cavity walls and Attic), and the well fitted triple glazed windows and doors.
Next we needed to gain as much free, (solar) and renewable energy as possible, from the PV panels on the roof, and through the windows, roof lights and the Conservatory.
Finally, by reducing the energy load in this way we could install a very efficient and cost effective heat source, (with an Air Source Heat Pump), good controls, (fully weather compensated with thermostats in each room), and a low energy distribution system, (with under floor heating in the extension and radiant panels on the internal walls in the existing.
Benefits of work carried out
I’ve said it all above really. The house is comfortable, inexpensive to run, and isn’t emitting environmentally harmful greenhouse gasses.
Favourite feature
Architects play games that they don’t always tell their clients about. Somewhere in most of my buildings there’ll be references to traditional Japanese architecture and classic themes like inside/outside. The paving slabs in front of my office are laid in a nine square grid, (a ‘perfect’ form having a beginning, middle and end), are strongly reflected in the windows and mirror the notional tatami mat layout of the office itself.
‘Very arty farty’, as my wife would say, and all to do with order and the relationship between man and nature. It please me, completes the jig saw that is the process of designing and building, and costs nobody but me a bit of time and thought, and many years of learning.
-Technical, Ecotect results
-Reduce losses, (insulation and infiltration),
-Maximise/control gains, Velfac windows and doors, triple glazed and well fitted, cut out
drafts.
-Rooflights, making our own
-Living rooms to South, Utility to North.
-More glazing on ground floor
-Solar PV
-Best available energy source, efficient distribution system, good controls.
-Air Source Heat Pump
-Radiant panel (wall) and underfloor heating
-Wireless room thermostats and load compensating controls
-Lighting and Appliances, LED and ‘A’ rated
-Rainwater recycling
-Materials, natural, recyclable, long lasting.
Still to do,
-Green roof, and replace the existing Conservatory.
