R-Zero

ODCV Demo

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Occupancy-based Demand Control Ventilation
20
Floors
10
AHUs
200,000
sq ft
Total area
1,000
Design occupancy

The building

A typical 20-story commercial office tower. Ten air handling units (AHUs) each serve two floors, pulling outdoor air that must be heated or cooled before delivery.

The temperature gap

On a summer day, outdoor air is 95°F. The building must cool it to 55°F -- a 40°F differential that costs real energy for every cubic foot of air processed.

The hidden problem

Floors 3-6 are completely vacant -- unleased and empty. Yet their AHUs deliver the same conditioned air as fully occupied floors. Two AHUs running at full design capacity for zero occupants.

A day in the life

Scroll to advance through the day. Watch how occupancy varies dramatically across zones -- and how the building never comes close to its design capacity.

Morning ramp-up

Full-time tenants arrive between 7-9 AM. Hybrid tenants trickle in. The lobby sees a brief morning spike. Vacant floors remain at zero.

Peak occupancy

Even at the busiest point, the building holds roughly 200-250 people -- about 20-25% of the 1,000-person design capacity. This is the post-COVID reality for commercial offices.

Evening wind-down

By 6 PM, most floors are emptying out. Yet the building's ventilation system has been running at full design capacity all day long for all 10 AHUs.

Without ODCV

The building ventilates at constant design rates. All 10 AHUs deliver maximum outdoor air regardless of how many people are actually inside.

Waste on empty floors

AHU-2 and AHU-3 serve completely vacant floors. Each pulls in 1,950 CFM of hot outdoor air that must be cooled -- 3,900 CFM of unnecessary cooling load every hour of every day.

Constant maximum

Each AHU's outdoor air intake is pinned at 1,950 CFM -- the ASHRAE 62.1 design rate for 100% occupancy, regardless of how many people are actually present. Every cubic foot of that 95°F air must be mixed with return air, then cooled to 55°F supply.

The daily bill

Watch the energy and cost counters climb steadily. By end of day, the building has consumed significant energy conditioning outdoor air that nobody needed.

With ODCV

Now each AHU modulates its outdoor air damper independently based on real-time occupancy from R-Zero sensors. Total supply airflow stays the same -- only the OA/RA mix changes.

Empty floors: dampers close down

AHU-2 and AHU-3 drop to area-only outdoor air (1,200 CFM OA each). The remaining 1,800 CFM is recirculated return air at 75°F -- far cheaper to cool than 95°F outdoor air. 38% OA reduction per AHU.

Busy floors: right-sized

Even the busiest floors (17-20) at 50% occupancy only need 1,575 CFM per AHU -- 19% less than the 1,950 CFM design rate. Every AHU saves.

The savings add up

Compare the counters to the previous section. The energy curve climbs much more slowly. Less outdoor air means a cooler mix entering the cooling coil -- and significantly less energy to reach 55°F supply temperature.

Same AHU, two strategies

Same air handling unit. Same occupancy. Same day. The only difference is whether the ventilation system responds to actual occupancy or runs at constant design rates. Use the dropdown to compare any AHU.

The visual contrast

On the left, the outdoor air damper stays locked open (red). On the right, it modulates with occupancy (blue). Try switching to AHU-2 (vacant floors) for the most dramatic difference.

Per-AHU savings tally

The savings delta grows throughout the day as this single AHU wastes energy on the baseline side while the ODCV side only conditions what's needed. Compare the cumulative kWh counters.

Monthly impact report

Extrapolating one day's savings across 22 working days per month, based on this building's specific occupancy mix.

0
kWh / month
Energy saved
$0
per month
Cost saved
$0
per year
Annual savings
0
metric tons CO2 / year
Emissions avoided
0
trees equivalent
Annual CO2 offset
0%
Ventilation energy reduction

Vacant floors contribute the largest share of savings -- they receive zero benefit from ventilation yet consume 20% of the baseline energy. Every zone type saves, but underutilized spaces save the most.

Monthly savings by zone type
Energy: needed vs. saved

ODCV doesn't sacrifice indoor air quality. ASHRAE 62.1 compliance is maintained at every point. The savings come purely from eliminating over-ventilation of under-occupied spaces.

Ready to see what ODCV can do for your building?

R-Zero's occupancy sensors and ODCV platform deliver measurable energy savings from day one.

Learn more