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[Part 2] The 5 minute guide to an 'Open System' BMS, cost-effective & easy to implement. What we learned after 30+ years of trial and error...

[Part 2] The 5 minute guide to an 'Open System' BMS, cost-effective & easy to implement. What we learned after 30+ years of trial and error...

Part 2/5: Creating the simplest and most elegant BMS solutions for Residential Developments.

In my travels to Central London I keep discovering a new residential site being built that I haven't noticed the week before and this can only be a good sign for the construction industry and the UK economy as a whole.

With all these developments under way in the UK I'm sure this is a topic of interest for Building Consultants and BMS Service Providers.This is the reason I have decided to write this second part of the guide about the most common BMS design challenges for Residential Developments. [Part 1 can be found here]

Everything I'm about to share with you will look surprisingly simple and at the same time uses products readily available on the market.

1. The metering equipment.

What to look for when selecting MID approved Heating, Cooling and Electricity meters.

All the specifications I have read over the years require that each dwelling must be individually submetered. Having this facility is great for the tenants as they can be in control of their utility consumption and equally good for the landlord when it comes to utility billing.

So what makes the difference between having a metering solution that just meets the spec and having a great metering strategy in place? Here are my top two recommendations to any solution designer to look for, therese are all tried and tested:

  • If MID approval is needed for the electricity meters then I would encourage you to look for those meters that have the MID approval when used to monitor one 3 Phase circuit but also when used to monitor three x 1Phase circuits. This gives maximum flexibility to distribute the meters around the building. Did you think all MID electricity meters have this? Well not really, just have another look  and you will see that most electricity meters are MID certified only when used to monitor 3 Phase circuits.  When I looked deeper into this I discovered that there are not many manufacturers out there that offer this and I was very surprised to discover that the most cost effective ones were also the ones to have this feature. After a long period of searching and trialling many different meters here is the one that we found to be the best MID Approved 3Ph & 1Ph Modbus DIN rail meter.
  • In regards the MID approval for heating and cooling meters I have come across a requirement that is only apparent once the meters have been in service for several years: 'How one can check if the meter calibration is still valid and should the meters be re-calibrated periodically?'  Tenants have every right to question the metering equipment that is used for their billing and so what should building owners respond to this? After I have spent many weeks talking to the National Measurement & Regulation Office turns out there is no requirement to have a heat meter re-calibrated under the Heat Network (Metering and Billing) Regulations 2014. However Regulation 5 states: Where a meter to which these regulations apply is installed it must accurately measure, memorise and display the consumption of heating, cooling or hot water by a final customer. And also, Regulation 8 states: Where meters or heat cost allocators to which these Regulations apply are installed the heat supplier must so far as possible ensure those meters and heat cost allocators are — (a) continuously operating, and (b) properly maintained and periodically checked for errors. The best course of actions for landlords when challenged to re-calibrate the meters is to simply check if the meters are still operational, a visual inspection is necessary but also the ability to interrogate the meter using some form of communication protocol so that at least the meter internal measured temperatures can be compared against the pipe temperatures can be recorded and compared. Each manufacturer is very reluctant to give away their tools of checking the meters so after a very long search we found that the best way to interrogate the meters is using an M-bus to Modbus converter that would give any BMS engineer the ability to check the internal meter readings, here is the best tool we have found for this: MBUS TO MODBUS RTU RS485 CONVERTER

2. The BMS controls fitted inside each dwelling.

How to best converge all BMS controls inside each dwelling such as the metering and underfloor heating/cooling, all without extensive wiring.

  • Use Modbus protocol to bring all the metering together since the electricity meters come with built-in modbus while the heat meters can be converted to Modbus using the MBUS TO MODBUS RTU RS485 CONVERTER 
  • The water meter pulsed outputs can also be picked up using Modbus enabled Digital Input IO modules ideally having the smallest footprint so that they can fit in consumer units, here is an example of an RS485 modbus IO module able to read up to 8 pulse counters.
  • Keep it neat and tidy by minimizing the cabling around the dwelling. Using a wireless solution that has long range, that is modbus enabled and can fit in electrical distribution panels or near the underfloor heating manifold is ideal. Here is the best product we have found suitable for this: Wireless RS485 modbus bridge.
Everything I have shared with today you are answers to questions I have come across in my career and being able to solve these has provided our company with the ability to select only the most suitable products and offer the best possible solutions to our clients. 
Previous article [Part 3/5] The myth of the open BMS protocol... what you should be aware of
Next article [Part 1] The 5 minute guide to an 'Open System' BMS, cost-effective & easy to implement. What we learned after 30+ years of trial and error...

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