Passive House protocols, when applied to the design and construction of a building, will dramatically reduce the energy required for heating and cooling. This reduced energy for heating and cooling lowers the overall energy use significantly. As a result, the amount of energy used for water heating, lighting, refrigeration, appliances/electronics (plug loads) become more impactful and more important to manage. Consider the example below.
The Pie Chart on the left shows the breakdown of operational energy required, in a 12-month period, by an average detached single-family residence in the U. S. (Data from U.S. Energy Information Administration). The purple segment shows that the energy required for Heating/AC represents 54% of the total operational energy use. The Pie Chart on the right shows the breakdown of operational energy of the same average residence when the envelope is sealed and insulated to PH standards. By comparing the purple segments of the two charts, you can see that the energy required for Heating/AC has been reduced dramatically (70% in this example) to only 16% of the total. Note that the entire Pie Chart on the right is also significantly smaller. The 70% drop in Heating/AC energy required has reduced the total operational energy required by 38%. The total area of the Pie Chart on the right is only 62% of the area of the Pie Chart on the left. Now, consider the impact on other segments of energy usage
The actual operational energy required for each of the other segments has remained unchanged between the two Pie Charts, but because the total energy required (represented by the Pie Chart on the right) is smaller, the other energy segments have become, as noted above, “more impactful and more important to manage”. The impact of Water Heating (burnt orange color) has gone up from 17% to 32%, and the impact of Appliances/Electronics (light blue), which is largely plug loads, has gone up from 21% to 38%. On the right hand Pie Chart these two segments now represent 70% of total operational energy use.
When the building envelope is up to PH standards the overall operational energy required is dramatically lower and other energy savings measures become higher priorities. With PH envelope performance, actions such as switching to a heat pump water heater (HPWH), or efforts to manage plug loads with power-strips, timers, sensors, and behaviors have a greater impact on lowering operational energy usage and reduce the renewables required to reach net zero energy.
Author: Jay Gentry