Energy Math

by Rick Barnett

Energy Math

Global carbon emissions dropped with the onset of Covid-19; however, with the increase in human activity in recent months, emissions are on the rise again. Additionally, the annual increase in carbon pollution over the past 60 years is about 100 times faster than previous natural increases. With the acceleration of this growth, the possibility of a 1.5* C warming peak may have passed. 

The Biden administration released robust climate goals and a $14 billion budget proposal for emission reduction and clean (renewables + nuclear) electricity. Without adequate support for a Clean Electricity Standard or a Clean Electricity Performance Program, however, the administration might have to accept a lower budget and more conventional measures like tax incentives and regulation to drive the energy transition. Running against the clean energy goals, future demand for electricity is certain to rise faster with EV’s, building electrification, and renewable energy for new end-uses such as space heating, space cooling, water heating and process heat.  

For success, the US must cut emissions 2160 MMt (from 5160 MMt in 2020) down to 3000 MMt by 2030. Also, electricity generation (4100 TWh in 2020) must increase from 40% clean (1700 TWh in 2020) to 3700 TWh: this requires at least 2000 new TWh to be on the grid in 8 years.

A clean electricity future requires widespread replacement of fossil fuel generating facilities with solar and wind farms. A logical start would be to close all coal plants, which produce 3 to 5 times more emissions per TWh than natural gas. Although half of the 500 US coal plants are on track for closure, the rest are still profitable and essential to providing a reliable supply. The unlikely scenario of closing all coal plants in 8 years would cut less than half of the 2160 MMt needed.  

In 2020, coal generated 23% of the electricity supply, about 950 TWh. In contrast, solar provided only 2.3% (95 TWh) of the 2020 supply. Even if 950 TWh of solar could be financed, construction would require over a million acres (4 times the size of Los Angeles) and nearly a billion panels. A 23% solar grid cannot be built in 8 years, and it would only provide half of the 2000 TWh of new clean electricity needed for the 2030 goal. If wind was assigned to provide the other 1000 TWh, current generation of 340 TWh from 65,000 turbines would have to triple with 130,000 new turbines.  

Because emissions and energy demand are too high, and clean energy powers only 40% of the grid, Biden’s 2030 goals cannot be achieved with existing decarbonization measures. A clean energy future requires belt-tightening on the demand side. One untapped option involves improving residential thermal performance. On average, more than half of a US household’s annual energy consumption is for space heating and air conditioning. Much of this is lost via thermal leakage. 

Thermal imaging for heat loss in homes

A typical house needs to be reheated every 6 minutes, compared to every 60 minutes for a thoroughly sealed home, such as an Airtight House from Passivhaus. Good thermal performance has been widely demonstrated in “zero energy ready” and “zero net energy” new construction. Although uncommon, proven thermal systems can also be installed on existing homes.

The emphasis of more than 600 utility efficiency programs is promoting high efficiency products (such as EnergyStar) rather than targeting thermal leakage. In view of residential demand trends, thermal efficiency is the only option for pulling excessive demand into better balance with a clean supply. 

Fortunately, local contractors can use commercially-available products to eliminate wasted energy. Thermal retrofits are labor-intensive, producing at least $5000 in local payroll per project. A continuous thermal seal cuts demand by at least 5000 KWh (17 million BTU) every year for the average home’s long life. More than 100 million US homes would significantly benefit from upgraded thermal performance. A home’s reduced energy demand can be measured and monetized with home performance scoring, such as the RESNET HERS index.  

Eliminating thermal leakage is an overlooked opportunity for utilities to decarbonize and create unsubsidized jobs. Space conditioning energy drives up a utility’s peak demand expense, when energy cost can be double. At the right price, a utility could buy demand reduction from local contractors rather than more energy. Because a retrofit relates to the home rather than the occupant, thermal retrofits can be offered inclusively to all customers without new expense. Improved dwelling comfort, value and resilience are additional benefits of “thermal optimization”, introduced in this 2016 Climate Institute report. Retrofit cost depends on location and techniques, and the utility’s choice of performance level: the feasibility of utility-financed thermal retrofits is locally determined.  

Community leaders everywhere can encourage building contractors to engage energy suppliers about measurable demand reduction, and the potential for new local jobs. 


Check out the EEBA Team Zero Inventory of Net Zero Homes to learn more.


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