Measuring Program Results with Sensors: 12 weeks later…
For the past year, Global Green has been conducting outreach via the use of eco-ambassadors. In order to track results from the program remotely, we have piloted technologies for reducing waste in multi-family residences. From our work this year, an average of 1.5 lbs of food waste per household were diverted from landfills and we’re aiming for eco-ambassador programs to achieve results in the same range. In cities where the costs are borne in the trash bin (and not compost bin) then economic savings can be achieved by closely tracking and achieving diversion results. We’re currently testing out and modeling what is possible.
Testing reports on sensor technology is an opportunity to improve the information in a field where data is in scarce supply. Sensors provide site-specific, real-time waste stream data. They’re also compatible with the larger energy/water/waste reporting platform used by thousands of multi-family operators nation-wide, EPA’s portfolio manager.
For this pilot, the sensors, provided by Enevo for the pilot period, measure fill rates and collection frequency. Remote sensors were installed as part of a multi-family food waste project to assess the volume of the of material going into the trash, recycling and food scrap bins.
In total, two multi-family buildings located in the City of Santa Monica were equipped with remote sensors on each of the 3 waste streams, recycling, mixed (landfill), and organics. One participant was a national Real Estate Investment Trust (REIT) and the other is a Southern California affordable housing nonprofit. The sensors were installed and collecting data for twelve weeks.
These sensors are measurement tools which allow us to remotely conduct waste audits of the bins involved in the pilot project by both tracking the rate of waste generation, as well as collection frequency and efficiency. Some visual inspection is recommended to go along with sensor data to ensure the correct materials are going into the accurate bins, as well as to monitor contamination.
By tracking fill rate and collection frequency data, sensors can help to:
- Inform when waste pickup is optimal
Track the volume of waste in each bin over time
Ensure waste is picked up only when the bins are full
What data is gathered?
The information collected through sensors can help property management companies, haulers, and cities to optimize waste collection service to save money and encourage further diversion.
After a pilot period of 12 weeks, the data supports that sensors offer both environmental and economic benefit.
The graph below illustrates data provided by the sensors and the related software that shows containers fill level over time for the mixed waste (landfill) stream at one of the pilot buildings. The first graph displays container fill rate over a 1-month period, a snapshot of the entire 3-month pilot period displayed in the second graph below.
From Data to Action
The data reveals waste collection most often occurs with bins underfilled to less than 50% of full capacity. The observation of under-utilized bins leads to 2 different potential actions:
Action 1: Reducing collection frequency
Action 2: Reducing bin size
Action 1 is to reduce the number of waste collections per week. By reducing collection frequency by 1 or 2 days, this represents a potential monthly cost savings of:
Cost Savings = Cost of Each Pick-up X # of Reduced Pick-up per month
Using the City of Santa Monica's rate structure of:
Cost Savings = $171 * 4 (assuming one reduced pick-up per week)
Then cost savings are about $685 and $1,370, respectively.
Sensors can thus help identify necessary changes to improve waste hauling efficiency, and the waste cycle itself by incentivizing waste reduction. Additionally, sensors assess the residents’ participation in recycling and potentially optimize the waste stream and waste management decisions.
Action 2 is to reduce bin size.
Bin Size Rate or Larger Bin – Bin Size (Rate) for Smaller Bin = Cost Savings
In the City of Santa Monica program, we are generally working with 2 cubic yard bins. If these were reduced to 1.5 cubic yards, then costs are reduced. First, this option needs to be carefully considered to make sure that enough bin “space” is left to prevent overfilling. Secondly, once “peak demand” is determined then cost reduction measures can be considered and implemented. For example, if the collection cost of 2 cubic yards bins costs $650, and the collection of 1.5 cubic yards bins costs $550, then there is potential to reduce costs by $100 per collection. Further, if this bin were collected twice per week for one year, this is a cost savings of $10,400 per year.
To read this blog on the Global Green site, click here.