John Avenson Residential Project, Westminster, Colorado | At 9 years old John became interested in the concept of green building on a family tour of the Colorado Indian Cliff Dwellings, where the park ranger told him that the Indians dug their caves on the side of the cliff as the winter sun kept them warm.
The Avenson Residence, a single-family, detached, three-bedroom home, was built in 1981 as a research house by the Solar Energy Research Institute [SERI, the forebearer for the National Renewable Energy Laboratory]. After touring these dozen homes, John Avenson contracted and helped build his improved home surpassing the building codes of the time by covering the envelope with 1.5 inches of PolyIso panels creating R19 walls. The house did not have good quality airtightness due to the 1980s standards but great orientation. John Avenson a retired electrical engineer of AT&T Bell Labs for 42 years, has continued his work by making this home his passion project and education center.
John took the PHiUS Alliance and German PHI courses for Passive House building consultation and has continually upgraded the house to be an exceptional high-performance zero energy and zero emissions retrofit home. The Avenson Residence is saving approximately $1200 to $1400 per year. In 2019, air-tightness tests showed approximately 25% improvement – with air leakage down to 406cfm from 537 cfm in 2017. The residence’s level of air leakage is about one-fifth the amount of a new home built in Westminster in 2024 to meet the energy code requirements.
This SERI floorplan design has no plumbing fixtures on the south side of the house to avoid needing vent pipes through the southern roof that could have prevented an array of PV panels from being installed. The front door has an air-lock corridor that prevents the cold prevailing winds from cooling the house in the winter. All windows were originally wired for electric automatic shades. The shades act as a one-way valve to let the winter sun heat in but not let heat out. The external walls were lined on the interior with brick thermal mass to absorb the sun’s heat. More thermal mass was obtained by building the house around a hidden 11-foot-tall rock box at the center. [Common rocks, can be ideal for thermal energy storage (TES), which involves storing solar heat for later use.] The rock box allows solar heat to pass through the three floors of 5’x5’ glass panels and is absorbed by the thermal mass and then slowly released into the home. In 2015, the walls were upgraded to R55 with U-0.12 (U-value) Krypton gas-filled quadruple-pane windows. Air leaks were also sealed across the house. A CERV (conditioned Energy-Recovery-Ventilatory) was installed that constantly provides fresh air keeping CO2 and VOC levels low. The slow release of the heat reduces the need for conventional heating. A 9000 BTU (3/4 ton) cold-climate Air-Source Heat Pump (ASHP) provides backup heat for the whole 2000 sq ft house using only 200 watts while operating on most winter days.
The 14 kW PV solar panels including battery backup generates approximately 20% more power than John consumes. Excess energy goes to the grid, providing him with a utility bill credit. The house is off-the-grid via the battery back-up from sun-down until about midnight every day avoiding peak usage electrical rates. The house has a hybrid electric ASHP water heater which extracts warmth from the house air and is three+ times more efficient than a regular electric water heater.
John extended his green initiative to his landscaping. There is minimum tree shading in the south providing Solar Access to the building and spreading Bio-Char over his blue-grass lawn which absorbs CO2 out of the air to enrich the soil and reduce watering.
John Avenson’s interview with Colorado Public Radio (CPR)
A BIG thank you to our Promotional Partners for their support
| Bruce Bohannan | Wes Geary | Sean Cunningham | Berry Rosenberg |
| Tom Vincent | Craig Maierhofer, Alpen Windows | Cody Farmer, Mainstream Corp. | HomeSeer |
| New Energy Colorado | Dale & Marla Kloeckner | Mark, Cathy, & Lizzy Boshears | Bill Lucas-Brown |
| Andy Wildenberg | Steve Stevens | KK DuViers | Danica Larson |
| Ron & Gretchen Larson | Nick Perugini | Joni Jackson | Carol Bouwer |
| Hilary Morland | Joann Herricks | Mark Rogers | Ron Kiefel |
| John & Pat Bringenberg | Mark Miller | Keith Alpert | Frances Rew |
| David Takaahashi | Rich McClure | Tracey Bennett | Mark Nimlos & Shelia Townsend |
| Todd Collins | Michele Ryan Sannes | David Brockway | Angela Kantola |
| Peter Ewers | Martin Volker | Chuck Kutscher | Rick & Chris Coen |
| Chester Pauls | Peter Eberle | Sam Anderson | Nancy Kellogg |
| David Bowen | Dallas Cox | Rebecca Cantwell | Ellen Dibble |
| Allen Best | Kim DeVoe | Margaret Pauls | Leslie Glustrom |
| Sarah Boe | Jen Grauer | Jeanne E. Puerta | Dennis Brachfeld |
| John Andrews | John Avenson |
AVENSON RESIDENTIAL PROJECT | SHARED FOUNDATIONAL SPONSORS
