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4 Answers

Is this a valid way to measure heat load?

Our manual J calculation said that the heat load of the house is about 30K at about 65 degree delta T. (It was more precise than that but I don't have the report handy, so I am going from memory.) I am hoping to confirm that the actual load is not too far away from that before we get into really cold weather.

In Mechanicals | Asked By Reid Baldwin | Dec 5 16
6 Answers

Mini Split Questions

-I'm in zone 4, midwest US, and am about to buy a ductless split system for my main structure and the addition I'm finishing now. I am concerned as three of the five rooms I am putting them in are pretty oversized (~2600k btu load cooling, using the 6k heads) and the rep is saying I should go with the H2i. He said if I never need the low temp operations, the heater was worth the money.

In Mechanicals | Asked By Mike M | Dec 5 16
12 Answers

Is this a reasonable solar bid? — and other questions

Howdy folks,
I got my first solar bid today, from Consolidated Solar Technologies. For a 3.2 kW ground-mount array in Albuquerque, New Mexico, the total cost before the federal tax credit is $16,300, and $11,410 after the credit. This works out to $3.56/watt.

One thing I worry about is that their calculator shows a higher projected output than PVWatts does. Their tool showed 6,500 kWh yearly, but PVWatts shows 5,844 kWh. This is supposed to be a net-zero-enabling array, so I don't want to underproduce. I'm using 6,500 kWh for my yearly usage

In Energy efficiency and durability | Asked By Nate G | Dec 5 16
14 Answers

How to employ a mixing valve in a closed loop radiant heat system

We are just wrapping up the new roof on my project house and now its [past] time to turn our attention to HVAC - or, more specifically this time of year, Heating! This 1975 house came with radiant heat ceilings as the only source of heat. Recently we have been having night time lows in the teens and daytime highs here in Northern Nevada zone 5 at 5000 feet are usually in the 40's. I have done some preliminary calcs on heat gain/loss, and plan on doing a full Manual J model before laying out any cash for components.

In Energy efficiency and durability | Asked By Roger Smith | Dec 1 16
17 Answers

Another crawl space in the Northwest

Hello all, I have a 1150 sq ft rambler house in Fall City, Washington (near Seattle), zone marine 4c. I am currently in the process of redoing the crawl space. I have pulled the damaged and rodent infested insulation down, and removed the town vapor barrier. It seems I had some rodents that were digging past the foundation and getting into the crawlspace, ruining everything.

In Energy efficiency and durability | Asked By David Meyer | Nov 28 16
1 Answer

Rodent-proof soffit vents

Hi,
what is the best way to create a rodent proof soffit vent air intake? I am looking for really durable products. My concern is that rats and squirrels could eventually gnaw through even hardware cloth. Any stainless steal products that people can recommend? Thank you very much.

In General questions | Asked By Matthias Paustian | Dec 5 16
11 Answers

How important is a thermal break between a house foundation and an attached garage foundation?

Our footings were poured today for a new house and attached garage. The walls of the basement foundation (9') and garage foundation are scheduled to be poured next week.

Looking over the plans, our concrete sub is worried about the 7" thermal break between the basement and garage foundations (no physical connection) as currently drawn on the plans. The separation is there in order to allow us to attach 5" of Roxul Comfortboard 80 to the basement foundation (we'll be doing the same for the whole exterior perimeter of the basement foundation).

In Green building techniques | Asked By Eric Whetzel | Dec 2 16
3 Answers

Insulating an unvented roof

I'm looking to finish the ceiling (underside of roof rafters) in a workshop/barn that is only heated when occupied. I'm in IEEC zone 6 (upstate NY) so it gets cold. Can't pull off the roof because it's relatively new and in great shape. Any work has to come from the inside. Right now there's a double layer (6") of rigid polyiso insulation in each rafter bay. The insulation if faced on both sides with fiberglass impregnated black paper (nasty stuff). There's also about 3" of open space between where the insulation stops and the edge of the roof rafters.

In Energy efficiency and durability | Asked By David Wittner | Dec 5 16
6 Answers

Mini-split energy usage

My first winter with a Mitsubishi ductless 15000 BTU (MSZ-GE15NA & MUZ-GE15NA). It's been in the low 30s in Seattle the past few days. I attached the electric usage recorded by my e-gauge. In the past (warmer temps) the usage curve is pretty flat. Now it's pretty jagged. Is it working properly (i.e.efficiently)? Thanks.

In Mechanicals | Asked By S K | Dec 5 16
4 Answers

What is the relationship between air source heat pump and indoor heat pump water heater?

I am sure this has been analyzed here before, but I want to check my reasoning. A criticism of heat pump water heaters is that they cannibalize the home heat source and so during the heating season perform exactly as electric water heater efficiency. However if the heat is provided at COP 3 from an external air source mini split, then am I correct that the heat that is being "borrowed" by the heat pump water heater is also COP 3 and so year round the heat pump water heater functions at COP 3 or better?

In Energy efficiency and durability | Asked By ven sonata | Dec 5 16
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