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Are You Being Responsible with Numbers?

numbers math uncertainty building science

Numbers. We deal with them all the time. They come at us from all directions. We believe them. Or we don't. We throw them out and expect others to believe us. Those of us who work in the field of building science have a responsibility to understand them, to use them wisely, to share them appropriately. But there's one word that describes the irresponsible way that numbers are used much of the time.

Amazon to Use Server Farm Waste Heat for Office Heating

computer data center server farm waste heat

This morning in my ASHRAE newsletter, I saw an interesting story about a cool thing is planning to do with heat. Amazon, in case you didn't know, is a heavy user of computers. Not only do their run their online store but they also have a popular cloud computing service. Computers turn electricity into kitten videos, celebrity tweets, and waste heat. And that last one is huge.

RESNET Changes Training Policy with Interpretation

HERS rater training confirmed rating

The RESNET board of directors last week issued Formal Interpretation 2014-04 (pdf). If you're on RESNET's mailing list, you may not have noticed this one come through on 24 September because they send out so many emails, but it's an important one to look at. It's titled "Clarification of Training Ratings" on the RESNET website. But it's more than a simple clarification. It's a change in policy that doesn't have to go through public comment since the board issued it as an interpretation.


On the Edge: The North American Passive House Conference

north american passive house conference phius 2014

The 9th annual North American Passive House Conference happened two weeks ago in the San Francisco Bay Area of California. The Passive House Institute US (PHIUS) has been holding this conference every year since 2006, and it just keeps getting better. I've been to the last three now, and it's one of my favorite events of the year, right up there with Building Science Summer Camp (Dr. Joe Lstiburek's conference) and Possum Drop (the New Year's Eve party I go to each year in Georgia). This year's conference seemed especially good because of the direction PHIUS is taking the passive house movement in North America.

An Energy Recovery Ventilator Is NOT a Dehumidifier

ventilation energy enthalpy recovery ventilator erv humidity

A common misconception about the energy recovery ventilator (ERV) is that it's good for humid climates because it helps to dehumidify a home. It's usually the better choice for a humid climate when you're trying to decide between an ERV or an HRV (heat recovery ventilator) but not because it's a dehumidifier. It is not a dehumidifier. Here's why.

All Over the Map — The Imprecision of 24 California HERS Ratings

stockton research project hers rating discrepancy grange

A home energy rating is supposed to tell you how energy efficient your home is. A certified home energy rater goes to the home and collects all the data relevant to energy consumption in the home (well, all the data included in the rating anyway, which is almost everything). Then they enter the data into energy modeling software and get the results: consumption for heating, cooling, water heating, lights, and appliances plus this thing called a HERS Index. But what if the results were off by 50%, 100%, or even more?

This Thermostat Setting Can Cost You Money and Make You Sick

air conditioner thermostat fan on temperature 600

I've been experimenting with my family lately. Or is it, experimenting on my family? In either case, I've got the data to confirm something I wrote in a 2011 article. But before I tell you what I did, first let me show you what happened. Here is Exhibit A: A Moisture Mystery. What do you think happened to cause the humidity (blue data) in the air in our condo to rise like that?

My Big Fat Oversized Air Conditioner

hvac oversized air conditioning system massive enormous condenser

Back in 2009, I had a new air conditioner installed our condo. The previous one was an ancient 25 years old and barely limping along. It wasn't cooling much, and the summer electric bills had risen. So, I did a Manual J load calculation on our condo to find out what size we should replace it with. I wanted to install one that wouldn't be too big so it would have long runtimes and keep our place cool and dry. Well, I put one of my new data loggers to use this summer to find out if I succeeded. The (doctored) photo below, which is not our condo, might give you a hint how well I did.

Why Is RESNET Limiting Its Options for Improvement?

How can RESNET improve the consistency of the HERS Index?

In case you haven't heard, last year RESNET created a task force to look at ways to improve the consistency of results among certified home energy raters (aka HERS raters). One week ago, executive director Steve Baden sent an email about the latest developments in the process. He also attached a document titled Quality Improvement Working Group RESNET QA Options (pdf) that outlines the areas of consensus and gives three options for changing the way quality assurance (QA) is done. Unfortunately, there's a glaring omission from the list.


Moisture and the Quirkiness of OSB

oriented strand board osb permeability

Oriented strand board (OSB) gets blamed for a lot of problems that are really the fault of the designers and builders. Part of the problem, of course, is the perrenial confusion between correlation and causality. OSB hit the market as we really started getting serious about insulation and air sealing. As I described in the story of painters refusing to paint insulated homes, building assemblies that keep the exterior sheathing and cladding colder restrict its ability to dry. Is that the fault of the OSB? Or the insulation? Or the lack of a vapor barrier? Or something else altogether?

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