Expensive control systems + value engineering = poor control and efficiency
Modern BMS systems are not compatible with DH and zero carbon solutions for the following reasons:
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Cost - the extremely high capital and licence costs of BMS systems means that only the 'must have' for operation goes in and you never get the 'nice to have' for energy efficiency. It costs so much in cash and time to get anything done that it never gets done. For example, one should be aware that BMS controllers are deliberately throttled back to be slow, just so they can charge you more to release the throttle. This is daylight robbery.
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Reliability - the impression is that at modern BMS system must be seriously resilient. However that's not the case. Resilience comes from building in redundancy, and from having enough decentralisation that a problem at any one point will not take down the while lot. We have seen first hand local authorities left for days without access to any sites because of IP clashes within BMS networks.
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Data - Saving data points every 15 minutes is a joke when it comes to fault finding. You need to be analysing control loops that run over seconds. The problem is again cause by costs - its simply too expensive to put in extra storage space or the licence fees to connect to external data stores such as Dropbox (if that's even possible with BMS)
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Restrictive - External services, such as Dropbox, are extremely useful. However BMS systems live in a closed world that prevents one from connecting to external services - it would mean one could circumvent the expensive channels and that wouldn't do.
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Complicated - Its all or nothing in the sense that you can't just start with a low cost single function and work up. For example, BMS systems are way too complicated (and expensive) to use in the domestic field. In the IoT world it is a very simple matter to remotely monitor boiler temperatures licence free, but through BMS it is restrictedly complicated and expensive requiring one to sign up to contracts or lose visibility.
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No Support - we have been unable to find anyone at the major BMS controls companies who is able to talk technical to us to discuss new functions. As one of the major HIU manufacturers in the UK, with the best independent performance figures, you would think we could at least arrange a phone call, technical to technical. It has proved impossible, and our belief is there isn't anyone available. The support is farmed out to installers who simply do not have the desire to engage with anything other than the calls that earn money.
If we are to stand any chance of achieving zero carbon in buildings, then the normal BMS channels need to be ditched in favour of lower cost, open-source, control systems. There simply isn't enough money to afford to upgrade the existing systems to something close to fit for purpose in terms of efficiency.
The phrase 'take back control' applies to the controls industry more than any.