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How can I best convert amount of construction materials for a building into associated greenhouse gases and equivalent energy generation that would cause the same emissions?

Hi Energy Central Community.

I am working on an article related to industrial heat and net zero. I began digging into Apple’s Campus 2 “Spaceship” and came across lots of facts and figures on the construction of this new, circular building.

I am seeking assistance in helping calculate the entire C02 and a relatable equivalence for our readers. I made some calculations below based on the figures and would love a volunteer or two good at such calculations to review my work as well as help in the measuring of glass (any glass manufacturer experts) and the overall CO2 calculation. 

Here you go:

  • Apple’s Campus 2 contains 3,000 curved glass panels, 31,000 tons of steel and 60,000 tons of hollowed out concrete.
  • On average, 1.83 ton (1830 kg) or (4034 lbs) of CO2 were emitted for every ton of steel produced.
    • Per my calculation: 31 million kg or 68,335,519 lbs of CO2
  • On average of 927 kg (2044 lb) of CO2 are emitted for every 1000 kg (2205 lb) of portland cement produced in the U.S. materials, a necessary part of the manufacturing process.
    • Per my rough calculation: 60 million kg or 132,277,357 lbs
  • Each of the 3000 curved glass panels measures 46 feet long and 10.5 feet wide. This type of glass requires heat of over 1500 C of 2700 F. 
    • Manufactured in Gersthofen, Germany and shipped to Cupertino
    • The pieces that are to be used as the exterior ring are cold-bent at 270C in a 220-ton furnace-style device that was built for this particular project.
    • I found 8.39 tons of CO2 per ton of glass manufactured
    • I found a calculator that converted the dimensions to a standard single pane window equivalent to 4.6 kg or 10.06 lbs
      • I need to convert the dimensions of the glass panel into a weight in kg.
      • I got 13800 kg equals 15 tons
      • 125 tons of CO2 or 113398 kg or 250,000 lbs was generated (I believe this is way lower than actual)

Total CO2 for Campus 2 is 91,113,398 kg or 200,862,876 lbs.


Overall, industrial emissions count for 22% of all GHG and that approx. 50% of industrial emissions is from industrial heat – the manufacturer of concrete, steel, glass, etc.


  1. I would love a glass expert to more realistically calculate the CO2 from manufacturing these glass panels
  2. Based on glass calculating, confirm my other calculations for a ballpark CO2 estimate
  3. Help me translate into practical and relatable terms an equivalent CO2 footprint. (ex. Power generation of a city for one year, million flights, etc)  


Glass is made by floating the molten silicon matrix on a tub of hot metal such as tin but there are other processes.  The process heat to produce the melted silicon and to heat the metal on which the glass sheet is floated are the primary starting points.

Assuming that natural gas is involved, the manufacturer of the glass shipped to the building will known how many BTU of process heat from natural gas are needed for each square yard of glass. 

This information is online. Start here.

"Glass manufacturing is an energy-intensive industry mainly fueled by natural gas"

Multiply the CO2 emissions from the natural gas as a factor of  tons of C02 produced per 1 million cubic feet of gas and then calculate the number of square yards of glass used in the building and the amount of process heat, generated by the gas to produce that amount of glass.

Bear in mind that there are all kinds of specialty glass products so any number you come up with will be at best a rough order of magnitude.

Video - how glass is made

Here are some CO2 coefficients for different types of fuels from the U.S. Department of Energy.

Basically, you get 117 pounds of CO2 from 1,000 cubic feet of natural gas.  For a million cubic feet of natural gas, multiply accordingly.  Now that you have this number, calculate how much natural gas is needed to produce the total square yards of glass in the building and then calculate the CO2 emissions.

And, if you want to cut CO2 emissions based on natural gas burning to make glass, investigate building the next new plant with electric furnaces powered by CO2 emission free nuclear energy.

Dan Yurman

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