Turning to Net Zero for Buildings – The HERS Index

Over the last few months my time has been occupied with travel and work. Relocation and working in construction has consumed certain amounts of time. In the process I have continued to learn and observe my working environment from the perspective of a mechanical engineer.

I have upgraded some of my technology, investing in a smart phone for it’s utility and ease of connection. However, this newer tech is still not the best for longer term research and curation efforts, such as this blog. I am happy to report I have managed to land a longer term residence which now will provide me the needed stability and access to resources, while I can set up my work space needed for more intensive endeavours.

Now relocated in Vancouver, I have a few projects in the works, and am able to get back to focusing some of my time into my own research and development, to which, is one of the major purposes of my blogging. Next week, on September 25th there is a luncheon course presentation I plan on attending regarding upcoming changes to the BC Building Code introducing The Energy Step Code. More on this topic later after the seminar.

In California we already see the movement on towards the construction of net zero buildings, as compliance to the 2016 Building Energy Standard which applies to “new construction of, and additions and alterations to, residential and nonresidential buildings.” (1) These rules came into effect January 1st, 2017. I will be reviewing this publicly available document and provide more insight and commentary at a later time.

One measure of rating homes for energy efficiency that I have seen often referenced and may be a tool for reporting and rating homes is the HERS Index as shown in the graphic.

Image 1:  HERS Index scale of residential home energy consumption.

As we can see from the scale that there is reference home, so there are calculation needed to rate a home, computer methods are available online where a houses data can be input for a curious homeowner, however qualified ratings are to be done by a qualified HERS Rating technician. These ensure by performance tests that a house meets standards in actual use and perform as claimed.

A comprehensive
HERS home energy rating

The HERS Rater will do a comprehensive HERS home energy rating on your home to assess its energy performance. The energy rating will consist of a series of diagnostic tests using specialized equipment, such as a blower door test, duct leakage tester, combustion analyzer and infrared cameras. These tests will determine:

  • The amount and location of air leaks in the building envelope
  • The amount of leakage from HVAC distribution ducts
  • The effectiveness of insulation inside walls and ceilings
  • Any existing or potential combustion safety issues

Other variables that are taken into account include:

  • Floors over unconditioned spaces (like garages or cellars)
  • Attics, foundations and crawlspaces
  • Windows and doors, vents and ductwork
  • Water heating system and thermostats

Once the tests have been completed, a computerized simulation analysis utilizing RESNET Accredited Rating Software will be used to calculate a rating score on the HERS Index. (3)

As buildings become more expensive and are asked to provide ever more services there will be a movement to make these building more efficient to operate and maintain. As we do more with less, there will be social impacts and repercussions. To some these changes may be disruptive, while enabling newer markets in energy efficiency, renewables, energy storage, micro-grids and net zero buildings, to name a few.

References:

  1. California Building Code Title 24 – 2016 Building Energy Efficiency Standards for Residential and Nonresidential Buildings.
  2. Understanding the HERS Index
  3. How to Get a HERS® Index Score
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