Getting my kitchen to be warmer than the garden

[WhyIsMyKitchenSoCold]

My kitchen is an extension on the back of the house, with two external walls, one wall that adjoins my neighbour’s extension, and the final side being an open entrance to the rest of the house. Downstairs is all open plan, which means that the temperature in one area of the downstairs really affects the temperature elsewhere.
The house is old, and cold – it’s got mostly double glazed doors and windows, but there are a lot of them, high ceilings and there is a cellar underneath which doesn’t help with keeping the place warm.
Specific issues in the kitchen include (though probably aren’t limited to) a very cold and uninsulated floor, big double doors which are reasonably well insulated but still big expanses of cold glass, radiators that are probably not powerful enough for the space, and a cooker hood that allows an enormous draft to come into the kitchen – I have disconnected that and insulated it with some tea towels shoved inside the cavity but that isn’t a long term solution.

I don’t really know where to spend money to improve the temperature, or how to decide what to prioritise. Is there such a thing as an “insulation expert”, who could come and look at all the different things that are wrong and help me prioritise what to do. I don’t want to spend a fortune on underfloor heating, for example, if the heat will all escape anyway. And anyone I ask just tries to sell me something that they can install e.g. a new boiler or radiators, because no one is going to say “what you really need is x” if their business is selling me y.

So what's the best way forward? Do I start with low cost things I can do myself, or is there someone who could help me decide what the best option is? I am dreading the gas bill arriving....

I'd start with thick, lined curtains and a huge rug.
Take the easiest options first

I would prioritise stopping heat escaping first if it were me. So I would check all around the window frames to see if there are any gaps etc. If I have curtains/blinds I would look to replace them with thick thermal ones.

My next step would then be getting the insulation in the walls checked. Then look to install bigger/more radiators.

Just my regular home owner opinion. Hopefully an expert will come along though!

Curtains across the back door is a thought. Would a rug in a kitchen be a horrible idea, though?
There aren’t any obvious drafts from the windows which have secondary glazing.
Bigger radiators is certainly an option but curtains sound cheaper!

Culprits for heat loss:
Draughts and gaps
Lack of back-draft shutter on extractor
Solid brick walls
Uninsulated ceiling (is there a room above or flat roof?)
Uninsulated floor especially if it's a timber suspended floor with an unheated space.
Large space to heat
Wooden doors.
Old double glazing.

Can you insulate the floors/cellar - you can stuff insulation between joists and staple netting or something across to keep it up.

Can you re introduce doors or thick curtains between rooms - if you still have double doorways as opposed to completely removed walls.

If you have a log burner they pack out a lot of heat once you get them going and burning hot and clean.

Get the floor insulated. It would make an enormous difference. There are companies which specialize in insulating floors. It wouldn't be a particularly tricky job to do yourself if you are quite handy. Just a matter of fitting some insulation boards between some battens.

Is there any way of reinstituting some of the internal walls / doors? Then at least you’d minimise heat loss from the rest of the house. I’ve always thought that some open plan layouts must have this problem - sorry, that’s not a helpful comment.

I'd start in the cellar by insulating the ceiling - you won't need to worry about the aesthetics, disturb the upstairs floor etc. You'd get thick sheets of insulating material that are screwed into the cellar ceiling, and can be covered with plasterboard if you prefer. On the external kitchen walls, any that don't have things stuck to them (e.g. cupboards) I'd line with insulation sheets, plasterboard and replaster. And great idea about big heavy curtain at the door!

To be honest I think you need a common-or-garden joiner, they'd know what is involved in getting rid of the different types of cold areas and you could ask to price separately e.g. how much for cellar ceiling, new triple glazed door, etc. They shouldn't be wanting to sell you expensive big ticket items like boilers etc.

An aga type cooker would solve the problem but they still cost money to run

My house is extremely similar to how you described yours and the kitchen gets so cold! Things that helped here are ensuring no drafts, even just getting some cheap silicone sealant around the windows, seal any gaps in the walls from sink/washing machine draining pipes and checking the extraction fan has a cover on the outside when not in use so cold air doesn't come in. Also putting a think curtain or blind up can help a bit. A well insulated floor would be the most beneficial fix but this isn't always an option for most people, including myself but if you can do it I'd highly recommend it.

My living room has 2 sets of double glazed patio doors. The difference between heat in the room with curtains open, and when curtains drawn is immense. I have heavy lined curtains. I can only imagine thermal (or thermal linings will be better). That's where I'd spend my money, plus a large outdoor rug, so that it can be easily cleaned. A thick, indoor rug would offer more insulation, but no fun to keep clean.

Dunelm do reasonably priced thermal curtains. They made a huge difference in my draughty bay window.

This is so helpful, thank you. I’m going to get a curtain and pole, and look at rugs. When this whole pandemic is over I will think about floor insulation too. Amazing - you’ve all been so helpful and generous with your suggestions.