For the Specifier
These are some practical tips and considerations for M&E consultants when designing BEMS. MC3E are
happy to assist with the design of BEMS so please contact us for assistance.
BMS or Discreet Controls?
A BMS is always superior technically but when budget restrictions apply then discreet controls can offer a
simple yet effective controls system. There are implications for the level of user interfaces as well as cabling
etc, please contact us to review.
McCool Controls would strongly recommend that the electrical Installation works associated with Controls
system be included in the Controls Specialists scope. Typically a lot of time is wasted on sites correcting
installation errors: time that could be used better for items such as further demonstrations and seasonal
commissioning. McCool controls can help advise you on the logistics of this so please contact us if you would
like to review.
Safety Interlocks - hardwired or Software?
Many Controls companies will supply software interlocks for such things as frost protection and High Limit
Protection – While this should be a feature of any good strategy it should only be complimentary to Hardwired
safety interlocks – If there’s one thing you should always specify is that all Safety features are hardwired and
fail-safe! If a controller fails or is removed the panel should still offer provide safety features.
Also it is advisable to specify Duct Frost Thermostats and HWS high Limit Stats as Manually Resettable to
ensure building Operators investigate the problem. This will prevent damage to plant and people!
Motor Control Centres Construction
There are various forms of panel and many regulations governing their construction. This is some simple tips
on specification but should you wish for further details please contact us.
Form 2 Panels will cover most installations. These are typically 2 box or 4 box solutions allowing access to
BMS controllers independently of the Starter Section.
Form 3 or Form 4 Panels which are compartmentalised allowing individual /Isolation (power Down) of sections
for both maintenance or in switchgear failure scenario. These are suitable for critical installations such as
Hospitals or Pharmaceutical plant and cost significantly more than the Form 2 Version mentioned above.
MCCs should only be from reputable suppliers, using reputable and EN Regulation Compliant Switchgear, and
supplied to site with test certificates. All cabling should be colour coded. All connections should be via ferrulles
and all cabling should be marked each end with cable numbers. All components within the panel and on the
fascia should be fully labelled.
Selection and sizing of Control valves is key as it doesn't matter how hi tech the control system or how well
constructed the strategy is, if the Valve is wrong you will not achieve the desired control. However there is no
point over specifying valves as it will lead to budget excess and impracticalities for installation. McCool Controls
can advise you on the installation of Control Valves for LPWH/CHW/Steam or whether for terminal units, large
plant or whether Pressure independent control valves are required. Please contact us for assistance.
When specifying actuators it is worth specifying that they have a lockable manual override facility.
Common Problem – Most Valve actuators cannot be installed in a downward inclination – It should be specified
that the are always kept horizontal or pointing upwards.
A remote Panel is always a good idea if the MCC is in a remote Location – Features might include a Panel
Mounted Graphic User Interface, Keypad, Summer/winter switch, Holiday/term Switch (if applicable) and plant
Run On timers with adjustable time selection (0-2hrs or 0-7Hrs) c/w cancellation features. Lamp indication for
the status of plant and for common fault indication is also advisable.
Embedded Web Server (I.e. part of a controller in the Panel) Interfaces offer a convenient method of providing a
PC based Graphic User interface, without providing a dedicated PC and Software licences. The browser needs
to be connected to the Site IT network (Ethernet) or to the Internet. Some restrictions of embedded webservers
would be memory capacity, max user limitations, limited histories etc.
PC based BMS webservers offer larger memory capacity, more processing power and can accommodate more
concurrent users (typically). Both Elesta RCO View Software and Johnson Metasys ADS software offer full
user functionality for remote web users whilst other Brands would have limitations on the web browser interface
as well as needing a second licence for a Front End (Cylon) – an operating software Licence and a Web Server
To discuss user interface options (such as dedicated Front Ends/Browsers/Touch Screens) as well as
networking issues (Ethernet/Intranet/GSM Modems/3G Modems) Please contact us.
Local Control? – A good Idea or Anathema?
Local User Interfaces are generally welcomed by occupants as it affords them ownership of their space.
However it is worthwhile having any local control integral to the BMS as opposed to independent of a BMS.
The temptation to put in hardwired stats or switches can often lead to wastage due to high set points and longer
plant running hours. Having the BMS as the Master control will lead to lower running costs as the local interface
can be governed by the central BMS.
The Interfaces come in many shapes and sizes for different applications. The Can range from Adjustable
Temperature sensor or a Plant Extension time to Aesthetically pleasing Hi Spec KNX type Controllers or LCD
Packaged units – Whats the right Application?
There are considerable offerings available for packaged plants in the market at present and these can offer a
smart turnkey solution for some sites. However their use should be considered on a site by site basis; for
instance if the site is significant enough for a Building Energy Management system to be deployed, or if there
is already a Site BMS in operation, then it would be for more beneficial to have directly compatible controls on
these units (where this is an option – for instance AHUs).
Whilst these packaged units can have Interoperability communications options (typically Modbus) they still
need the plant vendor for programming and commissioning and more importantly the Clients BMS contractor
will not be be able to maintain the controls on these for years to come.
So for sites with a BEMS - Ensure all controls are from the BEMS Vendor to ensure full control, monitoring and
servicaeabilty is available.
Pleasse constact us with your specific requirements.
System Interoperability – BACnet, Modbus etc
This is becoming more and more common in specifications. The most prominent Worldwide market force
appears to be the BACnet feature, although still not widely deployed in Ireland.
With technologies such as BACnet (or Modbus or KNX) the technology exists to have deep integration between
Building Systems from Multiple vendors via common communications Protocol. Basically the software
components of each system are based on a common set of features, the BACnet standard.
Care must be taken to ensure that network topography is correct as well as conformance classes etc. A vendor
shall be proposed to complete a common graphical User Interface if required.
Both of our primary BEMS Platforms (Elesta and Johnson) are BACnet as standard.
It is advisable that even if Interoperability is not required now, that the hardware being supplied now is future
proof for when it is required.
For more information on specifying BACnet installations, Modbus Installations, M-Bus Installations and KNX
installations in Ireland or for general Building Automation interoperability in Ireland please contact us.