Scalable, Reasonably priced Internet Zero Houses

The “Holy Grail” of vitality effectivity in residence development could also be net-zero vitality. To attain this coveted title, a house should produce as a lot vitality because it consumes in a calendar yr, usually through photo voltaic or wind.

“Internet-zero has been an obtainable purpose for many years, however nearly all the time at a prohibitive preliminary price,” stated Tom Danielsen, founding father of Danielsen Building and Power Administration, in Altaville, CA.  “That’s what I’m working exhausting to alter.”

Danielsen has been a builder since 1990, and specialised in vitality environment friendly development in ‘04.  Now, after practically twenty years targeted on lowering residential vitality consumption, he’s developed what he calls “net-zero for pennies.”

“Sometimes, attaining net-zero is exorbitantly costly,” stated Danielsen.  “I’ve spent the majority of my profession addressing that concern.”

That’s to not say that Danielsen hasn’t constructed and retrofitted houses with multi-million greenback worth tags.  He definitely has, and within the course of he’s developed a popularity for lowering the vitality consumption of constructions giant and small. However he’s all the time wished to show that by adopting net-zero because the purpose early within the design course of and retaining the challenge easy, the cost-per-square-foot distinction between a conventional residence and a net-zero residence will be mere pennies, with out sacrificing consolation or comfort.

Danielsen’s territory – east of San Francisco by about 100 miles – falls in California Local weather Zone 12, which experiences cooler winters and warmer summers than the Bay Space, for instance.  Pair that with a few of the highest utility prices nationwide, and also you’d be exhausting pressed to seek out a greater place to push the envelope on net-zero innovation than Calaveras County, CA.

Pilot challenge

In 2019, Danielsen was serving on the board of the Calaveras County Habitat for Humanity, a non-profit that helps folks get hold of protected, snug and inexpensive housing. His firm has retrofitted many current Habitat for Humanity homes with vitality environment friendly upgrades.  However it wasn’t till extra not too long ago that Danielsen took management of a brand new development challenge for the group, with plans to definitively show his “net-zero for pennies,” principle and, hopefully, use the house as a pilot challenge for a lot of to come back.

Danielsen introduced the Board together with his concept to construct an experimental residence. The purpose was to: a) show that his net-zero development methodology is replicable at scale b) show that the residence has the same square-foot price as traditionally-built houses and c) have an unbiased third-party measure the vitality efficiency of the house. The Board agreed.

“We construct and retrofit houses with vitality effectivity in thoughts on a regular basis, however we’ve by no means had the chance to use all the pieces we’ve realized on a single challenge and collect persistent vitality information,” stated Danielsen. “That’s what this specific challenge allowed us to do.”

Expertise Utilized

“In any dialogue of make a house environment friendly, the three fundamental subjects are inevitably the standard of the insulation, the best way the home is air sealed, and the star of the present – the HVAC system,” stated Danielsen.  “Every of those elements depends on the opposite two.”

Putting in insulation correctly is simply as necessary because the high quality of the insulation itself, in line with Danielsen. He makes use of Owens Corning L77 BIB (blown in blanket) insulation within the ceilings (R-40) and partitions (R-21). Spray foam, he says, generates too many VOCs within the occupied house, and batt insulation doesn’t carry out effectively.  He installs AMSCO low-E 366 glazed, argon stuffed vinyl home windows.  In the case of framing, two-by-six is greater than adequate, as long as the skin corners are “open.”

“When most individuals take into consideration air sealing, their thoughts goes to the climate stripping across the entrance door,” he stated.  “That is necessary, however the essential areas are these that may’t be accessed as soon as development is completed; the plumbing cutouts, framing cavities, the underside frame-plate to the subfloor, wiring inlets and register exchanges.  That is the place blower door air sealing assessments are received or misplaced.”    

A Completely different Tackle Ductwork

“We’re large believers in Fujitsu warmth pump expertise,” stated Danielsen.  “That doesn’t make us distinctive, however how we dimension and set up them does.”

Danielsen makes use of Proper-Suite design software program to calculate the load for every room in a home, giving him an correct load for the entire home, however simply as importantly, a load for every room, which he makes use of later to dimension and stability ductwork.

“Most design software program defaults to a 1.30 modifier, robotically oversizing the capability of the warmth pump,” stated Danielsen.  “We carry our modifier right down to 1.10. I would like the warmth pump to run 24/7.”

Danielsen explains that warmth pumps – or any HVAC gear for that matter – don’t attain full effectivity till they’ve been working for 10 or quarter-hour. An outsized unit that consistently cycles on and off by no means operates at its full potential. 

Danielsen explains that warmth pumps – or any HVAC gear for that matter – don’t attain full effectivity till they’ve been working for 10 or quarter-hour. An outsized unit that consistently cycles on and off by no means operates at its full potential.  As a outcome, he sizes his techniques for design situations and no extra. 

“Our method to putting in slim-duct techniques is basically simply finest observe, however some corporations don’t use the identical degree of element that we do,” stated Danielsen.  “In consequence, they sacrifice effectivity.”

“Our ductwork format is all the time a radial design,” he continued.  “We run duct straight from the plenum to level of use. Legs begin on the plenum, by no means branching off one other provide. This makes balancing a breeze.”

He additionally defined that by inserting registers on inside partitions and utilizing a really quick return, a pure convection present happens. As a result of the techniques run 24/7, the delta-T stays beneath 23°F, whatever the season. In consequence, air within the room doesn’t stratify.  Air temperature readings on the ground and ceiling present a differential of two°F or much less.

“Air ought to transfer at 400-600 CFM, producing little or no friction and conductive loss,” stated Danielsen.  “Air ought to transfer as quick as potential with out creating a lot friction.”

Lastly, sealing and burying the ductwork is extra necessary than many individuals assume.  anielsen likes to see 100% of the ductwork lined by insulation, however typically it’s simply not potential. They cowl all the pieces they can. As soon as duct sealant is utilized to the total duct system, Danielsen usually sees 5 p.c or much less duct leakage to the skin. 

Acquired the Inexperienced Items

Not one of the adjustments Danielsen implements are radical, however every small enchancment builds on the following, including as much as substantial vitality financial savings.  That stated, a decent constructing envelop, correctly-sized HVAC, sensible ductwork design and strong insulation are solely half the equation.  Deciding on and correctly putting in the proper home equipment and techniques is the opposite half.

The house doesn’t have battery storage capability.  Slightly, the photo voltaic array feeds the ability grid in the course of the day, and attracts from it at evening.

After getting the inexperienced gentle from the Board at Habitat for Humanity, Danielsen had a dialog with a neighborhood photo voltaic firm, Technical Specialty Options.  They provided to donate an eight-panel, 2.76 kW photo voltaic array that was put in on the 1,250 square-foot home. 

The house doesn’t have battery storage capability.  Slightly, the photo voltaic array feeds the ability grid in the course of the day, and attracts from it at evening.  The donated photo voltaic array would practically cowl all the ability used within the residence.

The warmth pump put in on the challenge is a single-zone 12,000 BTU/h Fujitsu H-Sequence 12LUAS1, providing as much as 21.5 SEER.

“We set up Fujitsu warmth pumps for a wide range of causes,” stated Danielsen.  “First, I really feel like they warmth extraordinarily effectively.  Second, if there’s an issue, there’s by no means an issue.  Their tech help and guarantee is the very best within the enterprise.  Their native help can also be excellent.”

Danielsen sources all of his warmth pumps at Johnstone Provide’s Stockton department. 

“Mark Whitlock, at Johnstone is completely sensible,” stated Danielsen.  “Good, instances ten to the energy of eight.  He’s helped with small issues and even large issues, like designing a VRF system at an enormous church.  I really feel fortunate to be working with each Johnstone and Fujitsu.”

To spherical out the gear checklist on the Habitat pilot challenge, Danielsen put in a 50-gallon Ruud warmth pump water heater.

Dream group

Danielsen Building and Power Administration was beneath the gun from the Habitat director to remain on price range.  The unique design for the house known as for a 60,000 BTU/h gasoline furnace and three-ton air conditioner.  Danielsen’s warmth pump design trimmed 50 p.c from the HVAC price, permitting more cash to be invested in different areas, primarily insulation. 

Over the course of the nine-month challenge, Danielsen labored together with his group of 4 installers, Alejandro Rodriguez, Hamberto Espino, Will Ibarra and Jose Rodriguez.  All of them have labored for Danielsen for over a decade, some practically twenty years. 

“I can’t give these guys sufficient credit score,” stated Danielsen. “They do phenomenal work, and actually see the worth in what we attempt to perform.”

As residence development drew to a detailed, yet another key participant got here on the scene. Torsten Glidden is a contractor for the U.S. Division of Power’s Constructing Applied sciences Workplace and is the technical lead on their Residence Power Rating program. His popularity as a good and neutral inspector supplied the proper end to the group.

Glidden was instrumental to implementing the SiteSage vitality monitoring gear that will finally inform the entire story of the residence’s vitality efficiency.  The system was put in on the house’s fundamental breaker panel, permitting real-time information assortment from each circuit within the residence.

The Experiment

As soon as the home was full and occupied, an necessary half of the experiment was to encourage the occupants to make their residence snug year-round.  There have been no restrictions on vitality use. Danielsen wished all of the home equipment within the residence for use in a fashion congruent with the typical American family. 

“Precisely monitoring all-electric houses is much simpler than monitoring a house with gasoline,” stated Danielsen.  With Torsten’s steering over a yr of information assortment, we had very particular numbers to match towards Pacific Fuel & Electrical’s (PG&E) annual utility information for the property.”

The info collected by the SiteSage system corroborated what appeared in PG&E’s annual True-Up invoice: extraordinarily low family energy utilization. Whereas the utility invoice confirmed the general energy consumption and photo voltaic array era, the vitality monitoring system supplied the true perception. 

The Outcomes

Over the course of the yr, the small photo voltaic array produced 4,571 kWh.  Not surprisingly, the water heater consumed essentially the most energy, adopted by the warmth pump, the dryer, the fridge and so forth. 

“We will see that the Fujitsu system operates constantly, utilizing between 400 and 600 Watts in the course of the winter, and between 600 and 800 Watts in the summertime,” stated Danielsen.  “Over the course of the yr, retaining the house snug required a bit extra than double the vitality it took to function the fridge.  That’s superb.”

Over the course of the yr, the small photo voltaic array produced 4,571 kWh.  Not surprisingly, the water heater consumed essentially the most energy, adopted by the warmth pump, the dryer, the fridge and so forth. 

When the utility’s annual True-Up invoice grew to become out there, all electrical consumption within the residence was portrayed in greenback values, adjusted for the ability generated by the photo voltaic array.

The house owner’s annual vitality expense was $574.  Home scorching water manufacturing price was $159, heating and cooling accounted for $128, and the dryer consumed $76 price of energy. 

“Within the state of California, a median utility invoice runs about $375 per 30 days,” stated Danielsen.  “Right here in Calaveras County, with comparatively scorching summers and chilly winters, the typical residence utility price is a minimum of that. It prices much less to energy this home for a yr than the typical residence in California for 2 months!”

The vitality information collected and verified by Glidden and PG&E are according to what Danielsen has seen on most of his development tasks over the previous decade.  As soon as supplied the information, board members at Habitat for Humanity might hardly consider the numbers had been actual. 

“What I discover most encouraging is that we’re not doing something loopy right here, and even when the photo voltaic array hadn’t been donated, this home would have price roughly the identical as a standard residence” stated Danielsen.  “There have been no ultra-expensive constructing supplies or strategies used.  We put in primary gear, employed finest practices and added a small photovoltaic array.  In actual fact, if we’d have added yet another panel to the array, the annual vitality price would have been lower than zero, making this a real net-zero property.”

The flexibility to construct net-zero houses at scale for roughly the identical price as ‘common’ homes adjustments all the pieces,” he continued.  “It offers folks the selection between shopping for practically an identical houses at a really comparable price, besides one residence may have no utility payments and a dramatically diminished environmental footprint.”