Two Core Principals of Residential Energy Consumption

"A home's purpose is to provide comfort and protection from the external environment." That may be true but it is a limiting statement. A home is where you watch TV with your family, play video games with your sibling(s), read bedtime stories to your kid(s), or cook with your spouse. A simple truth is that energy is required for all these activities and more. Determining how to minimize the amount of energy needed to achieve these activities is not so simple. However there are two key principals to start with, that will help you better understand your home:

1) Energy consumption is the result of factors like occupant behavior, building orientation and materials, and weather interacting at a given time. 

2) Once a home is built, occupant behavior is the most important factor and often the cheapest to improve.

1) Energy consumption is the result of factors like occupant behavior, building orientation and materials, and weather interacting at a given time. 

For example if it is a warm and sunny day, instead of using the air conditioner you may open the windows. Same comfort achieved but with no energy consumption.

Another example: if it is snowing outside, you will most likely have the heat on. How frequently the heat has to turn back on to maintain the comfortable temperature depend on:

• the thickness of the walls and the amount of insulation,
• how many people are in the house (humans consistently give off the heat equivalent of a 60 Watt light bulb),
  
• what people are doing in the house (walking around vs sleeping),
• how many electronics and lights are on (all electronics/lights produce heat when on), and
• the temperature difference between inside and outside.
  

2) Once a home is built, occupant behavior is the most important factor and often the cheapest to improve.

Helmut Krawinkler, a well-regarded professor in Stanford’s civil and environmental engineering department, who passed away in 2012, discussed the structure and systems of a building as being analogous to a person, e.g., the HVAC system is the buildings respiratory system. Just like a person, each home has a backstory that drives their performance. And just like a person, behavior is the main driver of performance. Take a 20ft wall. Shorter people can touch higher on the wall if they can jump higher than the tall person. <See 5'9" Nate Robinson Dunking: https://www.youtube.com/watch?v=sXXjrB9KH0s> Similarly, an energy efficient lifestyle in an energy inefficient home can consume less energy than an energy intensive lifestyle in an energy efficient home. However, if a tall person and short person can jump the same height, the taller person is able to reach higher on the wall. In reality, every person has a maximum height they can touch on this wall, which is in part dictated by their height. Similarly, every home has a maximum level of efficiency, dictated by how the home was built. <See DOE energy asset score: https://www.energy.gov/eere/buildings/building-energy-asset-score> Building and household characteristics, e.g., orientation of the home, window-to-wall ratio, and thermal mass, all dictate the efficiency a home can reach, i.e., natural reach; whereas, occupant behavior is the ability to jump.


Every building is unique; thus, requires personalized care when it comes to improving the performance of the building to improve the comfort and health of the occupants. Gemini specializes in personalized care for commercial spaces. For residential take a look at: https://www.hersindex.com/find-a-hers-rater/