Recent Q&A

• Avoiding the Global Warming Potential of Mini-Splits?

  There has been much discussion previously on the surprising global warming potential (GWP) of extruded polystyrene (XPS), at 1430. According to Wikipedia--so it must be true--the refrigerant R410A has a…

• Linseed Oil Paint

  Is this the most environmentally sound exterior finish for wood siding? This short video explains the process of finishing wood cladding with an all-solids (solvent-free) natural linseed oil paint. Linseed…

• Ventilation / heat recovery / energy efficiency

  This is a thought process about ventilation and energy efficiency, in ten steps: 1. According to ASHRAE 62.2, a house with 1,500 SF occupied area and two people needs 30…

• Radiant vs. Mini-Split

  Experts on this website advise against installing radiant floors in a high performance house. However, that feature is a homeowner request for a project that will have exposed concrete floors…

• Crash Course Video Series

  http://www.youtube.com/watch?v=XnXZzx9pAmQ&feature=player_embedded This link is the first of a series of videos about the relationship between economic growth and the physical world. The presentation is in simple terms and quite lucid.…

• Insulating a Slab on Grade from Above

  This could illustrate a reason to use a pseudonym, because I have lots of ideas and some of them may be half baked, but I’d like to invite commentary. Please…

• Alternative (Non-Foam) Outsulation Strategy Using Rockwool

  There’s a lot of talk about the benefits of exterior insulation, but also the downsides of rigid foam materials—that is, the chemicals involved, future disposal issues, wrong-side vapor barriers, susceptibility…

• Windows for Passive Solar (continued): Serious, Thermotech, etc.

  I am selecting windows for a house in Portland, OR, a marine climate. The heating demand is not extreme but it is a heating climate, and this is a passive…

• Space Heating and DHW combo: Is this efficient for DHW alone?

  In a climate where the heating season is less than half the year, would a combination condensing boiler and indirect water heater (e.g. the Triangle Tube Prestige Excellence) still be…

• Is engineered lumber more “green” than solid sawn?

  Anyone reading this website will be familiar with the green angle for engineered lumber, using wood more efficiently. And of course there are technical advantages to I-joists, especially for longer…