Energy Targets

EnergyUse-InfographicI am sure we have all seen graphics like these, giving us a pretty picture of what is one of the primary contributors to climate change, as buildings contributed nearly half of all the CO2 emissions in the united states in 2010.  Not to mention it gives us an idea of what kind of pace we are using our fuel sources, and as they become more difficult to obtain, costs will just continue to rise.  Energy usage in our homes is becoming a big deal as energy codes are becoming stricter and utility companies are being required to produce a certain percentage of their product by renewable sources and provide energy efficiency programs for their customers.

Related to home energy usage, I have noticed a lot of press on Net Zero Energy Homes and even attended a webinar by Matt Grocof who renovated a home built in 1901 and is now the oldest home on record to be a Net Zero Energy home.  Now most Net Zero homes are new homes as it is easier to build new rather than retrofit energy efficient systems into an existing home, hence the reason for my attendance on the webinar.  With more than half of the 113.6 Million homes in the United States, over half this number was built before 1980.  This leads to a huge potential of improvement in energy usage with our existing housing stock and that is why organizations like the Affordable Comfort Institute (ACI) have created the 1000 Home Challenge to create case studies of how to drastically bring the usage of our existing housing stock.  Therefore I was hoping to learn more about some of the retrofit strategies that were used to obtain net zero.

But first you have to know where you are, before you know where you are going.  Graphics like what’s shown above help tell us as a country where we are.  First we need a standardized metric to set targets for reduction, and what appears to be the best way to put everyone on a level playing field is to measure energy usage on a square foot basis. This is an easy way to set targets for new and existing homes early in the planning process as every house varies in size and construction type.  I have personally seen 900sqft homes use more energy than 2,000-3,000sqft homes.  Of course a lot has to do with the age of the house, which means the strategies for each will be different to bring the energy usage down, but this method will allow us to quickly find our place and determine benefits.

In Matt’s presentation he mentioned that most Net Zero Energy homes shoot for a target of 25 kBtu or less per square foot for total energy usage in the home.  So where do we stand, and what are some of the energy targets that are out there?  According to the 2001 survey by the Energy Information Administration in The Residential Energy Consumption Survey (RECS), the average single family home in the Midwest uses 49.5 kBtu per square foot of energy which includes both fossil fuel and electric usage.  Now this number varies by region due to climatic differences and age of the housing stock.  These are the numbers that are used by the organization Architecture 2030 as their benchmark to hit target energy usage for new homes that gradually step the usage down in order for the country to obtain a carbon neutral status.

Granted most of the standards apply to new construction to help reduce the strain on our existing infrastructure as new buildings and homes come online.  However they do help set a benchmark of where we need to bring existing home efficiencies.  So, lets take a look at what some of these standards are and where they lay:

  • Energy Codes (Based on REM/Design analysis)

    • IECC 2009 – 25.4 kBtu/Sq.Ft

    • IECC 2012 – 22.4 kBtu/Sq.Ft

  • Passive House - 13.3 kBtu/Sq.Ft

  • Architecture 2030

    • 2010 Target 24.7 kBtu/Sq.Ft

    • 2015 Target 19.8 kBtu/Sq.Ft

    • 2020 Target 14.8 kBtu/Sq.Ft

    • 2025 Target 9.9 kBtu/Sq.Ft

    • 2030 Target 4.9 kBtu/Sq.Ft

So, where did I start, and where do I stand in terms of the energy usage for my home and where do I need to go in order to meet the 1000 Home Challenge?  After our first year in the home (Sept. 2005 – Aug. 2006) our energy usage for the home averaged out to be 68.57 kBtu per square foot.  Of course we did not wait a full year before making energy efficiency improvements.  Now we are close to the end of our 8th year in the home, but year 7 ended up yielding a 28.31 kBtu/Sq.Ft.  However my actual energy usage still does not meet the modeled energy usage for the same home built today.  Although I still need to bring my usage down to 14.17 kBtu/Sq.Ft to meet the 1000 Home Challenge.

As you can see, I have already drastically reduced the energy usage in my own home, primarily with off the shelf, simple retrofit strategies.  So take this information as it is, however by making the reductions to our homes energy usage, we are keeping money in our pockets, making our home more durable to stand up to the test of time and making it a more comfortable and healthy place to live and raise a family.

About: Joshua Lloyd (115 Posts)

Joshua has a degree in architecture and is a LEED Accredited Professional that has worked in the design and construction industry for over 10 years, focusing his efforts on energy efficiency and building science. He has organized multiple events in Ohio to give young designers the opportunity to learn about “green” home design and produce actual projects. He was also a key player in Ohio’s first LEED for Homes Platinum project. Joshua is also a certified Building Analyst through the Building Performance Institute and performs home energy audits, assisting home owners in reducing their energy usage.

  • SLS Construction

    Nice piece Josh but I do have one small issue – the Passive House number is based on “source” energy use not “site” like the others. The actual number should be only 20% or 33% of the quoted number.

  • Josh

    Both the FAQ page and certification packet on the Passive House website don’t mention the numbers are based on “Source” energy use. But thanks for clearing that up, I was rather surprised to see how high the usage was as I was comparing it. However the heating & cooling loads are real low. Have you been involved in a Passive House project?

  • SLS Construction

    Primary = Source & sorry, I thought I attached the link when I edited it for the “13.3″ as my original guess was 20 to 33% of the number given –

    The full specs can be found here – but even it doesn’t list the one number but one can get it by adding all the allowances up.
    Came close, but no & not sure I want to after the breakup from the original Passiv Haus, though I won’t go as far as saying never – I personally think Challenge America has the Americanized version beat with less silliness