Rethinking Lifestyle

“It is a tragedy to have sight but no vision.”

The costs of various house construction features are easily estimated and widely used in planning a house. The quantification of savings available from energy conservation features is uncommon or rare. I was introduced to the calculation of the savings produced by energy conservation features in 2017 by Gio Robson, energy consultant.

As noted in previous articles in this series, calculating the savings produced by energy conservation features of a home provides the ability to estimate return on investment (bang for your buck). It also makes it possible to compare and select various features, and to calculate their contribution to energy savings as a portion of total house energy consumption (overall effectiveness). This information is invaluable when planning to build or upgrade a home.

I note that house builders are very quick to adopt new labour-saving equipment such as satellite-referenced survey and levelling equipment, rock slingers, excavators, cranes, concrete pumpers, skid steers, battery-powered drills, saws, nailers, drivers for screws and bolts, adhesives, foams, films, fasteners and more. Their efficacy is obvious.

The efficacy of energy conservation and generation features is not so obvious. Fortunately, powerful tools for monitoring performance are available for some features, and available in limited form for other features.

Our solar PV system includes an excellent monitoring and data storage system. I am able to see output in real-time on my computer (or smart phone), both for individual panels and for the whole array. A graph shows the current day’s output minute by minute for the whole day. Daily output is provided for the last 7 days. Monthly output is graphed for one year. Also, yearly totals show the history of generation since installation.

The system was installed mid-year in 2019. 2020 was a complete year, with the total generated energy measured at 7.99 kWh (or 7990 Wh), compared with the projected amount of 8000 Wh.

The bi-directional electricity meter shows two readings: Delivered and Returned. The meter adds to the Delivered amount whenever the amount of energy consumed by the house is in excess of solar generation. The meter adds to the Returned amount whenever the solar generation exceeds the house consumption. The meter does not add to either the Delivered amount or the Returned amount for the times when house consumption equals the solar generation. The conventional electricity meter provides only one reading, house electricity consumption. For a bi-directional meter, as I understand it, house consumption can be calculated with the following equation: House consumption = Delivered amount + Solar generation – Returned amount, with the same units for all items, typically kWh.

The energy savings of the conservation measures (insulation and air source heat pump) remain as projected numbers, not measured. However, there is considerable monitoring in place. Our Ecobee thermostat keeps a continuous record of equipment operation and key temperatures.

The energy consumption of the ASHP is presently not directly available to check whether or not it is working as projected. Hopefully this important information will be included in the future.

Monitoring and measuring equipment is becoming more sophisticated and more common. Interpreting the information may well be beyond the capability or interest of the average homeowner. However, there are companies offering annual checkup and maintenance services.

I have recently become aware of cold climate air source heat pumps (ccASHPs), which have been developed and tested recently. The intention is to increase the coefficient of production (COP) and to make the ASHP more functional at low temperatures. I have not yet found much information on this. Given the high projected return on investment and significant overall energy savings that I have described earlier, the development of ccASHPs is certainly welcome.

It is good to see improvements to important energy conservation equipment. It is good also to see the advanced state of monitoring equipment, with ongoing improvements. All are very helpful in reducing net energy consumption in our homes.