Office building with 1 AHU per floor

Existing building specifications

Building: commercial office building

Size: 10,000+ sqm

Floor layout: Mostly open plan with 30+ meeting rooms

HVAC system: one AHU per floor with VSDs, 15 AHUs in total; 400+ FCUs on all floors

BMS type: Trend IQ Vision

Control strategy: on/off

Control strategy with existing infrastructure to improve energy savings, comfort & air quality

This HVAC system is an ideal example of where we can enable on-demand ventilation control of the AHUs and FCUs via the BMS, without any additional HVAC upgrades. By installing our occupancy and air quality sensors (Base and Sahara Lite) we can use this data, when connected directly to the BMS via BACnet/IP, to design bespoke control strategies:

Energy savings via on-demand AHU fan speed control for each floor: the fan speed of the supply and extract fans in the AHU on each floor can be modulated based on live percentage occupancy levels on that floor. Energy savings come from reduced fan speeds as well as reduced heating/cooling needs during winter/summer.

Thermal comfort via on-demand FCUs in open plan spaces: this control strategy will vary the number of FCUs that are on/off, based on floor occupancy levels. This strategy reduces energy consumption, improves thermal comfort and reduces cold draft complaints.

Indoor air quality via enhanced FCU controls for meeting rooms: this strategy can improve indoor air quality (IAQ) and productivity in meeting rooms, with only one battery powered CO2 sensor per room. Once installed, the sensors are visible on the BMS automatically via LightFi’s semi-wireless IoT-BMS integration.

The business case:

By deploying LightFi technology in this building scenario, we can offer estimated total savings of:

c.18% savings of the total electricity bull or c.£125,000 per year at £0.29/kWh, and

achieve a 0.9-year ROI/payback period (including installation & BMS commissioning costs).

This building’s existing HVAC system enables floor-by-floor on-demand modulation of the AHUs. Using our occupancy level data, the detailed energy savings estimates are:

61.5% saving on the AHU fans (cubed power law),

19.7% savings on heating & cooling (linear), and

46.3% savings on FCU fans (open plan and meeting rooms).