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High-performance building: what actually matters in a Southern Oregon house

Written by Ben Treiger on . Posted in Articles.

High-performance building: what actually matters in a Southern Oregon house

A high-performance house is comfortable in July and January, uses less energy, has clean indoor air, and lasts. There is a lot of marketing around green building. This guide sticks to what Oregon’s code already requires, what the official sources say each upgrade does, and where you can go further.

A house is a system. Insulation, air sealing, ventilation, moisture control and heating all affect each other. Change one and the others change too. That is the way we build.

Air sealing and blower-door testing

Drafty houses usually leak at the attic, the crawlspace, windows and doors. ENERGY STAR says sealing and insulating can save up to 10 percent on yearly energy bills. The real result depends on how leaky the house is to start.

A blower-door test puts a fan in a doorway, depressurizes the house, and measures total air leakage. It also helps find the leaks. The result is given in air changes per hour at 50 pascals, or ACH50. Lower is tighter.

Oregon’s code requires new homes to have a continuous air barrier sealed to a checklist, or to pass a blower-door test at 3.25 ACH50 or less. One of the code’s optional efficiency measures asks for 2.75 ACH50, tested by a third party, plus heat-recovery ventilation.

Insulation

Oregon’s 2023 residential code sets these levels for new homes:

  • Attics: R-49.
  • Vaulted ceilings: R-30.
  • Walls: R-21, with insulated headers.
  • Floors over crawlspaces: R-30.
  • Slab edges: R-15.

New homes must also pick at least one extra efficiency measure. Two of the choices are R-21 walls plus R-5 continuous insulation outside the framing, or an advanced envelope with R-60 attics, R-38 floors and U-0.21 windows. For remodels, the parts you alter must meet current code as far as the existing framing allows. A remodel that opens walls or the attic is a good time to add insulation.

Heat pumps and heat pump water heaters

A heat pump heats and cools with one machine. ENERGY STAR says an air-source heat pump can deliver up to three times more heat energy than the electricity it uses. Cold-climate models are tested down to 5 degrees F, and ENERGY STAR suggests backup heat for extreme cold.

A ducted heat pump replaces a furnace and air conditioner. A ductless mini split works well in homes with baseboard heat, older homes without ducts, additions, and rooms that run hot or cold.

A heat pump water heater pulls heat from the surrounding air into the water. ENERGY STAR says it needs about 1,000 cubic feet of air space and a spot that stays between 40 and 90 degrees F all year.

Whether either one pays off depends on what you heat with now and who your utility is. Our rebates guide covers what is available in Ashland, Talent and Medford.

Fresh air: ERV and HRV

A tight house needs planned fresh air. A heat recovery ventilator (HRV) or energy recovery ventilator (ERV) brings in outdoor air and sends out stale air through a heat exchanger, so less heat is lost. The U.S. Department of Energy says an ERV also moves some moisture, which helps keep indoor humidity steadier.

Windows

A window’s U-factor measures heat loss. Lower is better. Oregon’s code calls for U-0.27 in new homes. ENERGY STAR says replacing old windows with certified ones lowers bills by an average of up to 13 percent nationwide. Your savings depend on the windows you have now and how much glass the house has.

Rainscreen siding and moisture

A rainscreen is a gap between the siding and the weather barrier, made with furring strips or a drainage mat. Water that gets behind the siding drains out, and the siding dries.

The EPA puts it plainly: “the key to mold control is moisture control.” Ground that slopes away from the foundation, a dry crawlspace, and indoor humidity between 30 and 50 percent all protect the framing.

Solar-ready

Oregon requires new detached homes to be solar-ready (ORSC R324.7). That means a junction box near the main panel marked “RESERVED FOR SOLAR,” with conduit run to the roof or attic. There are exceptions for small south-facing roofs and heavy shade.

Healthier materials

We use low-VOC and zero-VOC paints, finishes and adhesives, which release fewer chemical fumes. We also use GREENGUARD certified products (tested for low emissions), WaterSense fixtures and ENERGY STAR equipment.

Durability

Our approach is to replace rather than patch, and to build for the life of the house. A material that lasts longer and a house that uses less energy cost less over the years, even when the first cost is higher. We also recycle metal, cardboard and other waste, and donate fixtures and materials that still have life in them.

LEED projects get priority plan check in Ashland

Ashland Municipal Code 15.04.092 gives “top priority in the plan check processing” to new buildings, and to existing buildings whose repair or remodel cost exceeds half their replacement cost, that are pursuing LEED certification. To qualify, the permit application must show a LEED Accredited Professional on the project team, and the LEED checklist with the materials and systems for each credit shown on the plans. At the end, the LEED professional gives the city a final report confirming the project met the standard.

Green building certifications

A certification means someone outside the builder checks the work.

  • Earth Advantage is based in Portland. Its home certification has Silver, Gold and Platinum levels for above-code homes, judged on energy, health, land, materials and water, with third-party verification. A zero energy add-on covers homes that use solar.
  • ENERGY STAR certified homes exceed the minimum energy code by at least 10 percent, according to the EPA, and must be independently verified by a home energy rater.
  • Phius certifies passive buildings. For new homes the standards are Phius CORE and Phius ZERO, and for existing homes, Phius CORE REVIVE and ZERO REVIVE. Phius reviews the design early, and raters check the work and test on site.
  • LEED for residential, from the U.S. Green Building Council, awards points that set the certification level. Every LEED residential project must include a LEED Green Rater, who does the required on-site verification.

Each one adds rating fees and paperwork, so ask about them before you commit. A blower-door test can be done on any house, certified or not.

Thinking about a high-performance home?

If you want to talk through what would make the biggest difference in your house, I’d enjoy that conversation. Fill out the contact form; it reaches us right away and we respond within a day. If you’d rather call, the office is 541-300-8118. The chat on this site can answer questions, pull up costs, code and similar projects, and send your request to the office too.

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