heating review · next retrofit
Book the loft hatch first
The survey estimates 265 W of heat loss through the hatch, slightly more than through the floor. Sealing it costs £180, takes an afternoon, and can happen next week. The bay window has a larger estimated loss, but secondary glazing costs £1,180 and has a three-week lead time.
The bay window has the largest estimated loss
These estimates use a 20°C difference between inside and outside. They compare the size of each loss, not the savings a finished job will achieve.
element, loss single-glazed bay window, 410 uninsulated loft hatch, 265 suspended timber floor, 240 front door and letterbox, 155 chimney with no cap, 120
Which measure should be booked first?
The three jobs below have current installer access and quotes. Rank their estimated loss against cost, lead time, and disruption — not as promised savings.
Estimated loss: 265 W. The installer can do it next week.
Estimated loss: 410 W. The internal panel leaves the sash untouched.
Estimated loss: 240 W. It makes sense only before the planned refinish.
The January draught-proofing may already be helping
Four weeks after the 12 January work sit below five earlier weeks at similar outside temperatures. At 4°C, separate straight-line fits put the post-work readings 43 kWh a week lower. I excluded the shortened boiler-service week. This suggests a reduction, but four post-work observations and no control house cannot estimate its size.
outside average, before, after 2.1, 604, 3.0, 588, 3.4, 561, 5.0, 512, 6.1, 470, 2.6, , 542 3.8, , 498 5.2, , 470 6.4, , 449