When calculating Scope 3 emissions for waste generated in a commercial building, it is crucial to incorporate detailed data on waste types, disposal methods, and strategies for recycling and reuse. This blog will walk you through the process with an example calculation, focusing on dry waste, wet waste, and the waste diversion rate.

---

Step 1: Annual Waste Data Collection

A commercial building generates waste in different streams such as dry waste (e.g., paper, plastics, metal) and wet waste (e.g., food waste). To quantify emissions, we also need to consider waste diversion strategies like recycling and reuse.

Sample Annual Waste Data

Waste Type	Annual Generation (tons)	Diversion Rate (%)	Disposal Method
Dry Waste	50	60	Recycling (60%), Landfill (40%)
Wet Waste	30	50	Composting (50%), Landfill (50%)

---

Step 2: Emission Factors

Emission factors are critical for estimating emissions. Below are sample factors:

Disposal Method	Emission Factor (kg CO₂e/ton)
Landfilling	500
Recycling	50
Composting	20

---

Step 3: Emission Calculations

The calculation involves splitting waste streams based on diversion strategies and applying the respective emission factors.

Dry Waste Emissions

• Total dry waste: 50 tons
• Recycling (60%): 50×0.6=3050 \times 0.6 = 3050×0.6=30 tons
  Emissions: 30×50=1,500 kg CO₂e30 \times 50 = 1,500 \, \text{kg CO₂e}30×50=1,500kg CO₂e
• Landfilling (40%): 50×0.4=2050 \times 0.4 = 2050×0.4=20 tons
  Emissions: 20×500=10,000 kg CO₂e20 \times 500 = 10,000 \, \text{kg CO₂e}20×500=10,000kg CO₂e

Total emissions from dry waste:
1,500+10,000=11,500 kg CO₂e1,500 + 10,000 = 11,500 \, \text{kg CO₂e}1,500+10,000=11,500kg CO₂e

---

Wet Waste Emissions

• Total wet waste: 30 tons
• Composting (50%): 30×0.5=1530 \times 0.5 = 1530×0.5=15 tons
  Emissions: 15×20=300 kg CO₂e15 \times 20 = 300 \, \text{kg CO₂e}15×20=300kg CO₂e
• Landfilling (50%): 30×0.5=1530 \times 0.5 = 1530×0.5=15 tons
  Emissions: 15×500=7,500 kg CO₂e15 \times 500 = 7,500 \, \text{kg CO₂e}15×500=7,500kg CO₂e

Total emissions from wet waste:
300+7,500=7,800 kg CO₂e300 + 7,500 = 7,800 \, \text{kg CO₂e}300+7,500=7,800kg CO₂e

---

Total Annual Emissions

Waste Type	Emissions from Recycling (kg CO₂e)	Emissions from Landfilling (kg CO₂e)	Total Emissions (kg CO₂e)
Dry Waste	1,500	10,000	11,500
Wet Waste	300	7,500	7,800
Total	1,800	17,500	19,300

---

Step 4: Impact of Recycling and Reuse Strategies

By diverting waste through recycling and composting, emissions are significantly reduced compared to sending all waste to landfills. For instance:

• Without recycling or composting, total emissions would be:
  (50+30) tons×500 kg CO₂e/ton=40,000 kg CO₂e(50 + 30) \, \text{tons} \times 500 \, \text{kg CO₂e/ton} = 40,000 \, \text{kg CO₂e}(50+30)tons×500kg CO₂e/ton=40,000kg CO₂e
• With current strategies, total emissions are reduced to 19,300 kg CO₂e, achieving a reduction of 51.75%.

---

Key Takeaways

1. Waste Diversion Reduces Emissions: Recycling and composting significantly lower Scope 3 emissions by diverting waste from landfills.
2. Data Management is Crucial: Accurate tracking of waste types, quantities, and disposal methods is essential for credible emissions calculations.
3. Continuous Improvement: Strive to increase diversion rates by encouraging reuse, better recycling, and composting practices.

This comprehensive approach not only quantifies emissions but also highlights opportunities to enhance sustainability in commercial building operations. By adopting effective waste management strategies, buildings can play a pivotal role in reducing carbon footprints while supporting a circular economy.