Remote energy monitoring of HVAC plant and electrical feeders in Sir Colin Campbell Building for the Environmental Technology Centre.
The University of Nottingham, Environmental Technology Centre (ETC) provide support and advice to small and medium size enterprise and the ETC is the conduit for them to demonstrate energy efficient technology and work procedures aimed at reducing the carbon footprint within industry and commerce.
They wished to relocate t-mac GSM/GPRS remote monitoring equipment from their previous accommodation where it had provided electricity metering data for demonstration purposes. The new building offered the opportunity to monitor the HVAC equipment in the plant room and collect system flow/return temperatures in addition to the electricity data monitoring of the water source heat pumps, system circulation pumps etc.
The heating and cooling within the building is provided by three water source, reverse cycle heat pumps and is distributed through a perimeter heating (radiator) system and heat exchangers in air handling units delivering heating or cooling according to ambient condition.
The heat pumps source water is from a lake at the rear of the building and overspill from the lake is discharged into the River Leen.
Heat pumps 1 and 2 have two stage compressors and are designed to operate according to demand; they supply the perimeter heating system and building heating/cooling from air handling units within plant rooms located elsewhere in the two sectioned building which is linked by a bridge over the road. Heat pump 3 provides domestic hot water services. The picture below illustrates the distribution pipe work from the heat pumps. The equipment is controlled from a central panel within the plant room.
Flow and return contact thermistor sensors were installed on the source water, heat pumps outputs, perimeter heating and air handling unit distribution pipe work and wired to configured inputs within the t-mac unit installed to the right of the control panel
Electricity meters located below the t-mac unit will monitor the control panel supply, heat pumps 1, 2 and 3, the source water pumps, perimeter heating pumps and the air handling unit pumps . The electricity meter enclosure also houses a wireless gateway which delivers temperatures from remote RF sensors in the ETC to the t-mac unit via the RS485 Modbus communications platform.
Each electricity meter provides 9 parameters of data which may be read on the meter displays or from the web portal.
Additionally, the ETC commissioned t-mac Technologies to develop a dashboard illustrating Live Heat Pump Monitoring at the Sir Colin Campbell Building (link below).
Recent maintenance work at the lake has allowed photographs of the water source heat exchangers to be taken.
The t-mac installation within the SCCB is retrofit, therefore the temperature sensors used in the plant room to monitor flow and return temperatures are type 10K3A1 thermistor contact sensors; it would have been uneconomic to consider the installation of pockets into the main system pipework. Due to the difficulty of installing additional sensor wiring within the building, the plan was to utilise wireless sensors, supplied by t-mac to monitor the ETC office and outdoor temperatures, but it proved to be a problem because of the concrete and steel building fabric and the location of the semi underground plant room and would only work successfully from the reception area, despite trying to boost the signal with an RF repeater.
For some time I have thought that use of spare telephony or ethernet cables in buildings may simplify the installation of sensors in refrofit projects and following discussions with Keith Baker ETC Director and John Hemingbrough ETC Project Officer they requested their Estates IT department to test the theory. This has proved to be a great success, the IT department provided RJ45 outlets adjacent to the positions for the ETC office and outdoor sensor, with similar outlets next to the t-mac equipment. The cables were patched through the Ethernet cable network. One slight problem was quickly resolved; we had to install an ADAM 4015T 6 channel modbus thermistor input unit during the original installation to accommodate all the temperatures we wished to monitor. Initially it was found that the outdoor sensor readings were worthless in freezing temperatures. Investigation highlighted that the thermistor temperature range of the ADAM unit is 0-100degC. This was resolved by wiring the outdoor sensor directly into a t-mac wired input previously occupied by heat pump 3 return flow temperature sensor, which always is within a positive temperature range and could be connected to the ADAM unit.