Hi both!

Appreciate the question. It's a good one. 

Firstly, you're right that we have started experimenting with Facebook ads in the last few weeks. It's something new for us, so we're testing different things, wordings, visuals, etc. The whole process is an experiment and we're working with some external partners on this who create and manage the campaigns. They can get quite creative as you can imagine!

Secondly, on the claims then. This is not an easy one. And honestly something we are continuously talking about internally. The challenge is "What is the baseline?", and every house / user is different. The 40% that you see on our website is indeed versus a gas boiler. We chose that baseline back then because most people come from a boiler when they get a heat pump. The 40% is the average we were seeing across all our users at the time, meaning some people save more and some people save less.
If you do the math, a boiler with gas standing charge roughly costs the same as an "average" heat pump on a flat tariff. So you could argue that our users on average save 40% versus an "average" heat pump in the UK.  

Averages are limited of course and I understand the gaps in them. The ultimate comparison would be comparing to a heat pump prior to Havenwise. But heat pump A can be a heat pump from a very advanced user who has written their own Home Assistant code. And heat pump B can be an ECO4 install on a weather curve that has been set much too high with 3rd party stats. Very different baseline, therefore Havenwise would lead to different savings in those setups. 
And what do you do if it's a new heat pump which has just been installed?
And what if this winter is much warmer or colder than last winter?
And what if the user behaviour has changed because a child was born or an extension was added?
And what if the user changed tariffs? 
Etc.
You can see it's getting complicated very quickly! All to say it's something we're aware of and we haven't cracked yet ourselves in all honesty. More work to be done on this.

Totally agree, @hcas.

I think there's a bit of a conflict, though. As you will have seen on this very forum, you now have quite a well-established reputation for up-front open and honest dealing, but that advert does nothing to burnish that. Speaking purely as a customer, I'd far rather you compete on reputation rather than price. I realise, of course, that that's difficult when a big saving is a natural attention-grabber, but I wonder if you could publicise a limited set of comparison scenarios rather than just one "benchmark" comparison e.g.:

• If your heat pump's controlled by thermostats Havenwise might save circa £xyz
• If your heat pump's set up well but you're on a fixed leccy tariff, Havenwise might save circa £xyz
• If your heat pump's set up well and you're already on a TOU tariff, Havenwise might still be able to shave £xyz off your bill.

Dreadful wording, but you get the idea. Still showing the benefit but, by comparing like with like, being straight with people.

@hcas majordennis is on the money for me in terms of what I'd expect to see when you are making claims of savings of 40, 50% etc. Would be much clearer and the last thing customers need in this industry is more smoke and mirrors.

@majordennisbloodnok and @benson Good suggestion! We'll look into that. Might take a little bit of time (busy season) but I agree we need to address that. Not only us, but industry-wide I think.