BMS Update: -60% Energy Cost

The customer had an aging and failing SeaChange BMS system that they were struggling to get support on. In addition to this their energy bills were sky high, which was assumed to mostly be down to their ground source heat pump.



The brief from the client:

• Upgrade the BMS system to something manageable, maintainable, and with an interface that could be used to see what was happening in the system.

• Install energy metering to see where the rogue electricity was going.

• See what could be done to reduce energy costs.

We started by splitting the project into two areas, BMS upgrade, and energy metering. If we have proper controls of the heating, and correct energy data, then by leveraging Loxone changes can be made to how it operates iteratively to improve performance.



The BMS:

The original BMS system was made up of premade modules to control different aspects of a heating system I.e. a module to control a Secondary Pump, another to control a Boiler, another for Secondary Circuits etc... These were split across several locations, with a main plant room with modules for controlling the heat pump, a boiler, as well as primary circuit pumps and mixing valves. Then secondary panels for controlling zone valves at manifolds.



We surveyed the system to break down the actual input and output list that was needed, and from here cost engineer the hardware required for control. We found:



Main Plant Room:

• 10 Pumps that needed controlling

• 3 Mixing Valves to control

• Heat Pump Heating & Cooling control

• Boiler Control

• Existing 10K3A1 temperature probes on all flow and return pipework



Heating Manifolds:

• Mains Valve Actuators to control

• 10K3A1 temperature probes in walls and floors for space heating and floor overheat protection.



From here we planned a Loxone upgrade reusing as much of the original hardware as possible. The main panel got a Miniserver, Relay Extension, Modbus Extension, and Neptronics units to transmit the temperature probe readings over Modbus. The manifold panels got a Relay Extension, Modbus Extension, and Neptronics units as required.



For the energy metering, as the various fuse boards were spread out with no existing cabling to utilise we used WiFi Modbus meters to monitor.



The Findings:

The heat pump was the culprit of the majority of the electricity load of the house as it was running at low temps through most of the day. The heat pump itself seemed to be fairly efficient, however the heating system had lots of different pumps in use, most of which were 1kW+, with around 9 running on average most of the day.



The Solution:

The house needed heating, so there didn't seem to be much we could do on the surface aside from a large and costly mechanical upgrade of the heating system to reduce the pumps and complexity. However the customer was on an off-peak low rate tariff (Intelligent Octopus Go) with a 7p rate for several hours overnight. The house was also very highly insulated, so we thought as a good test what if we didn't run the heat pump all day.



Instead we set the house (excluding bedrooms) to have a comfort temperature of 21°C through the day, but using the logic inside Loxone to allow the house to purposefully overheat by 2.5°C during the cheaper times. This would in theory mean the heat pump would heavily ramp up through the cheap hours, and then would hopefully only need to 'top up' during the day.



The Result:

This worked better than we could have imagined, almost all of the energy usage of the heat pump was shifted to the cheap rate, and in all but the coldest days of the year the house stayed above the 21°C line during the day. The outcome, the customers nearly £1,200 monthly bill during the winter reduced by 60% and the new BMS system paying for itself within 3 winters.