Client: JCB Power Systems Ltd Requirement: Induction air heating system Solution: Energy-efficient mechanical services package

The building is for the assembly of JCB power systems and the building measures 185m x 73m x 15.5m mean height.

The stringent design was to meet the high specification and low energy needs of JCB and the following criteria was to be met.

• Energy Efficiency
• Even Air Distribution
• Temperature Control
• Minimal Temperature Gradient
• Efficient use of solar and plant heat gains
• Aesthetically pleasing
• Minimal area for Plant
• Maintenance and ease of access

At the heart of the low energy Induction system is the ejector diffuser module which has no moving components or any component which requires maintenance at high level. The ejector box positioned at high level allows high velocity airflow at high level which then entrains the surrounding high level air and mixes this air into the deliverable air at the correct temperature.

There is a constant recirculation of high level air which evens the temperature gradient throughout the height of the building.

This principle is the most energy efficient method of recycling any heat gains from lighting, plant, personnel and any beneficial solar heat gain as the system is constantly recirculating all the beneficial heat gains. The high level temperatures are reduced and the heat loss from the building is minimised.

The Low Energy High velocity system provides an even introduction of heating and ventilation throughout the whole of the building.

This system is vastly superior to purely nozzle based systems which do not create an effective induction / recirculation mix of air. The mixing ratio of the induction air is 50% more efficient and leads to a more even temperature throughout the height of the building as a result.

RUNNING COST BASED ON CIBSE GUIDE B18. ISSUE 2 TOTAL BUILDING AREA

Building heat loss: 934Kw.
Building class: 4D
Degree days: 2357
External temperature:. -3
Internal temperature: 19
Building occupancy: 12 hours

Factors
7 days operation: 1.0
Intermittent: 0.55
12 hour day: 1.25

Base temperature (B 18.7) 19 – 3 = 16. Ratio 1.06.

Uncorrected full load (B18.16)
Eq = 24 x 2357 x 1.06 = 2726 Hours.
               19-(-3)

Corrected full load.
Eq = 2726 x 1.0 x 0.55 x 1.25 = 1874 Hours.

Qr = 1874 x 934 x 3600 = 6301 Gj/year
               1000000

Qn =    6301 x 1000000    = 211450 cu meters of gas per year.
          38.7 x 1000 x 0.77

Therms per year = 211450 = 77031 Therms Therefore at 20p per therm £15407 per year.
                                2.745

This equates to a staggering annual cost 10.5 pence per annum per sq ft with the building operating 12 hours per day & seven days a week.

CONTROL SYSTEMS
The building is be divided into four no. zones, with building management Control stations sited at the heater locations on the mezzanine areas. All linked to Air Handling gas units, fresh air and recirculation damper motors roof mounted extractor units. The outstation complete with all associated relays and contactors. A low voltage control cable will be run to each heater to initiate control relays situated within the Heater Control panel. Two number Temperature sensors working on an averaging basis will control the level of heating in each zone. A communications data loop will run round the building linking all the panels to a suitable office allowing the system to be linked to a pc

CONTROL LOGIC
The entire system will be controlled from the four (4) zones each providing a complete building management facility. The system can be completely automated to respond to the heating requirements in the Winter and automatically switch to ventilation during the Summer.

WINTER SUMMER CAPABILITY
During the winter the system would operate at 90% recirculation for maximum efficiency with 10% fresh air to provide a slight over pressure. The system is fitted with EU4 filtration. During the Summer months we have included for a roof mounted extraction system to allow the supply system to provide 100% fresh filtered air and with the extraction system removing 90% of this volume this will ensure the 10% over pressure is maintained.

CONCLUSION
The system provides the optimum comfort and the lowest energy consumption for tall buildings, and buildings with heights of 35 metres have been installed with the system dramatically reducing running costs.