Personal story:

Stuart is a retired professional engineer and electronics hobbyist and Helen is a GP.

Motivations:

Comfort and cost saving.

The original house was designed when energy-saving was unheard of, and had poor insulation, used high cost energy (oil) and very limited controls.  As a result it was not particularly comfortable and was expensive to run.

Property background:

Architect-designed two-storey detached house built in 1960s for previous owners at a time when energy was cheap and insulation barely a consideration. Original construction was brick and concrete block with no cavity insulation, and a shallow-pitched concrete-tile roof.

Savings

Hard to give a single percentage, but note that we now use less electricity in the winter than we used to use in the summer. Though the PV panels do make a contribution, they are not very effective in winter. The main effect is simply replacement of all light bulbs with leds.

Having the panels on the FIT is a good thing because as a result of the early tariff we are on, we are now cash-neutral for energy (not carbon neutral).

Key changes made:

A wooden extension was replaced by a 1990s brick/light-weight block two-storey annex.

Various internal improvements:

• New folding doors to kitchen and lounge.
• Removal of internal walls to make space more flexible.
• Provision of en suite facilities in some bedrooms.

Remaining external woodwork (e.g. fascia boards, wooden doors, windows) replaced by powder-coated metal or plastics, with similar appearance but much lower maintenance.

Measures installed in detail:

Loft insulation: to 200mm, simple but made a big difference to comfort

Cavity wall insulation: blown bead insulation added by previous owners but incomplete, now inspected and fully filled.

Double-glazing: now throughout and draught-sealed, all with thermal breaks.

Low energy lighting: throughout, almost entirely LEDs. Kitchen lighting runs on 12v supply charged by PV when available, done to prevent loss of lighting during (common) power cuts.

Remote control sockets: to simplify switching lamps and electronics and to reduce use of ‘standby’ mode

Natural energy harvesting: solar PV and solar hot water, massively reducing electricity demand and making as much use of own-generated electricity as possible. Water now pre-heated by PV (Immersun) and solar water heat prior to heating by gas. In summer, on sunny days, all water heating by own energy.

Wood-burning stove: installed (we have enough trees to use our own wood)

Hot water tank insulation: mains-pressure tank now massively insulated (located in garage)

Condensing gas boiler: replaced old oil-fired boiler and tank and removed associated chimney and flue.

CH circulation: changed from ‘single-pipe’ to ‘two-pipe’ system, increasing level of control possible; intelligent ‘A’-rating circulation pump.

CH controls:

• Intelligent control system adjusting circulating temperature according to outside temperature plus other software provisions to minimise wasted heat (owner-designed and built, but commercial units are available).
• Individual soft-zone room thermostats/programmers with radio-operated valve actuators, TRVs on all other radiators.
• Precise hot water temperature control using intelligent thermostat, with tempering valve to reduce flow temperature to kitchen tap.
• Hot Water Priority – allows HW to be heated to 60 degrees (for legionella safety) whilst radiator temperatures are separately set.

Benefits of work carried out:

1. Paid-for electricity consumption has halved over the period, plus we have earned a 10% return on investment on the cost of solar PV panels. See: Stuart Gillies’ home electricity use
2. Gas consumption expected to fall by 20-25% compared to five-year average.
3. Comfort increased (less heat does not mean less comfort), the temperatures are more constant now.
4. Lighting quality increased due to LEDs (2700K colour, brightness, instant on) compared to CFL.
5. Overall, with solar FIT payments and import reductions due to efficiency, the house is energy-cost neutral (not carbon neutral).

Favourite feature:

The wood-burning stove!

Plus the graphs showing falling costs and the FIT cheques from EON.

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