Dan Johnson's blog

Exciting Building Products From Passive House Conference

In late September I gave a presentation at the 12th Annual North American Passive House Conference, organized by PHIUS, describing how heat pump water heaters can be used for combined space heating and water heating. When strolling the vendors' floor between presentations, I was pleasantly surprised to see an increase in the quality of Passive building products.

What's the Dirtiest Time of Day to Use Electricity?

Are there "dirty" hours when the California electric grid is producing a lot of CO2 per kWh, and "clean" hours with low CO2 output? It seems that midday should have lower CO2/kWh compared to other hours, if a large fraction of power across the state is generated by solar photovoltaics (PV) during these hours. Looking at data, Beyond Efficiency did in fact find a midday reduction in CO2 emissions per kWh generated for 2014 onward.

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