Southampton St low energy house

28/02/2026

I have invested in SMART HTC measuring kit, for new projects, and applied their calculation engine to my house and the HLP returned is exactly the same as I measured using my own DIY setup and calculations. Really pleased about that!

26/02/2026

Finally got my house air pressure tested last week.

A blower door fan seals into the doorway and depressurises the house to 50 Pascals — roughly equivalent to a 20 mph wind acting on the building. This exaggerates air leakage so it can be properly measured.

The result was 4.16 m³/hr/m² , which is pretty good.

For context, the general target for a new-build house is 8, and many older houses come in at 10 or higher.

I haven’t finished all the airtightness measures yet, but I wanted a test now to cross-check against the energy monitoring results — and I’m pleased to say the blower test broadly supports what the monitoring has been showing.

10/01/2026

On the way to EXCELLENT 😁

Well into the second winter of energy monitoring and my Heat Loss Parameter is 1.47. When I have finished the external wall insulation and conservatory it should hopefully be below 1.

07/01/2026

Hi followers, early last year I starting thinking about how the way I have done my roof could have broader benefits. The measured energy efficiency results are great.

Anyway after a year of researching, networking I have started a crowd funder.

Hi, my name is Tom, I am a self-builder and architectural designer based on Brighton.… Thomas Booker needs your support for Revolutionise home roof insulation

04/01/2026

Stair soffits finally filled sanded and painted. Really pleased with the way these complex curves (4 in total, each slightly different) meet the adjacent surfaces.

Exposed bungeroosh, to which I applied a light lime-mortar wash to reduce friability then rubbed some of the flints to highlight them. You can see the plaster line from the original stairs going in the opposite direction which I left as a feature to tell the story of the house.

Gone for panelling in the lounge and the opened-up-yet-dividing wall between the lounge and kitchen. I knew from the beginning I wanted this wall bright pink, so just did it and I love it. Before you ask the paints and materials in these decorative features are not necessarily eco (MDF and vinyl paints), but I am no saint either!

Bought a PM2.5 metres and for each of the three times I have used it whilst the stove is alight, levels are below 10 which is the WHO recommendation, UK guideline being 20, and I should add these are mean annual averages, not peaks.

04/01/2026

Just realised I haven't updated you on my table. Completed over Christmas 2023 (I did one coat of varnish every day over the Christmas break), and then stored and put into use autumn 2024 when the kitchen was finished. I can report it is still doing really well and showing no movement. 28mm thick and spanning 2.1m the old slow-growth fine-grained pine salvaged from the roof is so stable. With 10 coats of Bona Mega varnish it's incredibly easy to wipe clean. The stripes are from the soot on the surface of the rafters from the leaking chimney, now trapped in glue and sealed.

07/03/2025

3rd month of energy performance monitoring complete and spring is in the air. Average internal temperature 19.4 degrees with a standard deviation of just 1.03 degrees. Outside it have been 0.1 degrees below the long term average.

29/01/2025

185mm of insulation under the ground floor complete, ready for screed

29/01/2025

29/01/2025

After a year and a half of operation (invalidating the warrantee) today I commissioned the mechanical ventilation heat recovery (MVHR) system.

The system design required an airflow of 100.6m3/h, but this meant setting the power to 43% on the unit making it a bit noisy. On the basis it has run so far at 30% and my house has been warm and mould free I decided to set it at 37% as a compromise. The Testo405i in duct anemometer took a bit of getting used to, with quite variable results based on different airspeeds across the duct.

Flow rate for each room valve was set as a proportion of the room volume. To measure this I made a DIY hood out of a bucket and a bit of drainpipe with a vane anemometer taped to the end. This worked very well.

Also I found I had the correct flow rates to and from the rooms at 35% power, which was also the reason for settling on 37% rather than 43%. Plus at 30% so far, the unit has been drawing 17W which is right at the lower end of it's power consumption range, where it would like to keep it.

I set the boost to 62% up from 50% to reduce the humidity in the bathroom after showers and try to prevent my kids from opening the window so much, wasting all that heat!

All in all a bit disappointingly un-scientific. But as it is clearly doing it's job I decided to leave it at that.

The best bit was replacing the filters and seeing all the grime which hasn't gone into my lungs! Although a pointless though considering all the work I have done to this house, often not wearing a dust-mask!

09/01/2025

Findings from the first month of energy monitoring are better than expected. Internal temperature average has been 19.4 degrees, so 0.4 above target. External has been 7 degrees, which is 1.2 above the long-term average.

Actual heating energy used has been 998kW 2/3rds electricity and 1/3rd wood. Factoring out the temperature difference and extrapolating over a year gives an annual heating demand of 5,465kWh so 52kWh/m2(a), so I have halved the figure on my EPC.

When the rear conservatory and external wall insulation are complete I expect a further 45% reduction, bringing the demand a bit below my original 30kWh/m2(a) target, equivalent to an annual gas bill of under £500 including standing charge and hot water.