EnergyRealist

House Retrofit vs. Cement – I don’t know why that comparison came into my head.  I guess I was just wondering about the scale of what’s facing us.

The graph shows energy savings through retrofits, or home energy performance improvements (the left bar), compared to the energy consumed in making cement.  The center shows the cement used in China’s 3 Gorges dam and the right the yearly average (over 100 years) of US cement making.

The point is; we are making a difference, but it’s very small compared to the big energy users.  We need to face the big problems and do some big things, as well as going from house to house.

Some detail;

The retrofit number is based on some optimistic estimates, 10,000 retrofits in NJ per year, times 50, assuming every state does the same (a big stretch), assuming a 25% improvement (also a stretch).

Part of why this is a stretch is outlined in this article by the US Energy Information Administration. Houses are getting bigger and purely based on size are using more energy.

The 3 Gorges dam number is based on 16 million tonnes of cement used in the construction.  To put this in context China uses about 130 TIMES that much cement per year. See this Forbes article.

The US figure is more squishy, it comes from the same Forbes article, where China’s use over 3 years is shown as larger than the US use over 100 years.  It’s a staggering comparison. I’ve taken the lazy way of taking the 100 year average (45 million tonnes).  The actual picture is worse – at 86 million tonnes in 2017.

Also of interest is the amount of energy used in different world regions to make one tonne of cement.  About 860 Kwh in Japan, 1140 Kwh in Europe and 1470 Kwh in China and the US.  We can guess that China’s plants are inefficient, same for the US?

Bottom line; we’re doing something in residential retrofit, but – against all the strange denials floating around the internet – we need to do an awful lot more.