There are relatively few things I’d do differently “next time” but in a few cases new products have come onto the market which address some of the problems with the solutions selected.
Hot Water Storage
The stainless steel, heat pump compatible hot water storage cylinder made by Gledhill is a high-quality product but the insulation could be better. With no hot water draw-off the cylinder will typically lose 5 degrees overnight (60C @ 18:00 down to 55C at 08:00) even though the Plant Room tends to be hot (25C ambient – due to the passive solar gain (though there are no windows), the losses from the cylinder and the heating effect of the solar PV inverter and other electrical equipment).
An alternative to consider is one of the phase change “heat batteries” such as those from Sunamp. These are physically smaller than a comparable cylinder and are very well insulated. Losses from stored heat are much lower.
Lighting Dimmer Standby Power Usage
I really ought to measure exactly how much this is an issue but the DALI-controlled LED dimmers are always warm to the touch and must be drawing a few watts 24×7 even when the lights are “off”.
The newer versions of the MDT DALI Control IP64 Gateway include support for:
Energy saving function for switching off the ECGs in the 16 DALI groups (via additional KNX switch actuator)https://www.mdt.de/EN_Dali_Gateway.html
In other words, if the mains supply to the LED dimmer is wired via a KNX switch actuator channel, the DALI gateway can be configured to automatically switch off the mains supply to that dimmer (Electronic Control Gear; ECG) whenever the dimming value is set to 0%.