BER - what jump can i hope for

jmBuildExt

Hi, will be having an assessment carried out in the coming weeks but just wondering what kind of jump I can hope for in terms of BER.

The house is a ~90sqm 3 bed semi. It had a G rating. Cavity block build. Single glazing. Old light bulbs. Open fire and chimney up the middle of the house. Maybe 80 mm of old degraded insulation in the attic. Suspended timber ground floors. Gas fired central heating - with an old boiler.
So everything that warranted a G rating...

We have done significant upgrades and added 40sqm extension.
Extension is a double leaf 100mm blocks with 125mm xtratherm full fill cavity insulation between.
Course of thermal blocks on bottom where it meets the concrete and on top where it meets the roof.
140mm kingspan floor insulation below 50mm screed.
Architects notes say wall and floor to give min .21W/m2K U value.
Roof has 120mm of Kingspan TR27. Architects note says to give min U value of .18W/m2K
There is underfloor heating in extension only.
Gas stove. (sealed unit with twin flue going out the wall close by - the term for these types of gas stoves escapes me)

Existing house:
Replaced gas boiler for combi boiler (worcester brand, dont have any other details to hand). This provides hot water on demand throughout and serves the rads and underfloor heating. So 3 zones controlled by individual thermostats; downstairs rads, upstairs rads, underfloor.
All rads have individual thermostat valves fitted.
The chimney which ran through the middle of the house has been removed entirely from top to bottom.
Added 100mm external insulation to existing house.
Removed old attic insulation and replaced with 300mm earthwool above the ceiling joists.
A rated LED lights throughout.

All windows (including extension) are triple glazed UPVC.

Other info:
Did not insulate below suspended floor on ground floor. its Engineered Wooden floor and tiles above T&G floorboards.
There is no porch.
Ventilation is hit & miss vents (100mm diameter pipe) for extension, front sitting room, and 3 bedrooms. These have a simple internal shutter on them and a baffle on outside.
Main bathroom and kitchen has mechanical fan vented straight out the external wall.
An ensuite, downstairs toilet and utility room have no external walls - An individual (so 1 for each room) fan/extractor sits in the attic and vents out a vent tile in the roof.

I think thats it - Its just to satisfy my curiosity. As i say i will be having an assessment done in the coming weeks.

sydthebeat

make sure everything that cannot be seen can be verified by other means ie photographs, invoices, window certs, certifying architect / engineer sign off etc.

if it cant be verified, it cant be included, and default values have to be used.

jmBuildExt

Yep cheers architect/ engineer/ builder still on board. Should be no problem there.