Do this, not that… technical edition

Part of my job is that I get to see a lot of new, popular, and cutting edge things that people do in new homes.  Last week I wrote about some of the things that people see and fall in love with, and how some of these things can cause other problems while others integrate easily with energy efficient design.  This week I’ll cover some of the more technical details and talk about which ones I would and wouldn’t choose for my own home.

What I would skip….

None of these things are necessarily “bad”, in my opinion, but they all come with enough extra expense and or strings attached that I just don’t think they’re worth it.

Spray foam insulation in walls:  I’m not totally anti-spray foam.  It’s a really useful material that can do some things that other insulation can’t do.  When it’s used in roofs, ceilings, cantilevered floors, band joists, and other “hard to air seal” places, spray foam makes it very easy to get the building envelope right.  But our experience is that in walls, it doesn’t seem to make homes much tighter and the R-value isn’t any higher.  There are some exceptions:  wall paneling, walls that lack an air barrier on one side, other tricky details.  But in the typical home, you can get a similar R-value in the wall and a very tight envelope by using fiberglass or cellulose in the walls.  If you combine this with foam used in in the roof, floors, and band you can get similar performance for less money.

Hot water recirculation loops I’ve covered these in detail in the past.  They are actually great if you do them right.  The problem is that I just can’t get anyone to do them right.  The right way to control a recirculation loop is to use occupancy sensors or demand buttons in each bathroom and kitchen.  This allows the pump to only run when there’s a need for hot water.  If you also insulate the loop piping you will likely save a little energy and a lot of water.  The worst way to control the loop is to operate the pump all the time – your hot water essentially heats your house all year round.  Timers, smart controls, and temperature based controls haven’t been demonstrated to be effective enough for me (or, apparently, to the writers of the latest I-codes).  I’ve seen uncontrolled loops increase water heating energy by a factor of 6, and they are the number one cause of high-bill complaints that we’ve had in our Energy Star homes.  I would use a compact plumbing system or manifold system to avoid the need for a loop, or if I had to have one I’d use the demand buttons.

German windows:  You have to hand it to the advertising execs at Volkswagen.  They’re managed to convince us all that German engineering is superior to everyone else’s.  I’m sure it’s fine, but there’s no way it’s worth putting these windows on a boat and waiting for them to arrive (hopefully unbroken), dealing with the SI to IP unit conversion hassles, and taking a massive risk that the differences in labeling won’t prevent you from passing your code inspections.  North Carolina code is based on something called the NFRC (National Fenestration Rating Council) ratings.  Very few European windows are rated using this method.  You can build a house with a few windows that aren’t rated, but if all of your windows lack this rating, I cannot find a pathway through the energy code.  So far, I’ve never heard of anyone being denied a CO over it, but who wants to be the first?  There are a lot of quality, energy efficient windows manufactured in the US and Canada, and that’s what I’d buy.  I can work with a European window that is rated by the NFRC, but my advice is to get it in writing before you order.

Bonus rooms:  What’s wrong with bonus rooms?  Who doesn’t like cheap space?  Unfortunately they’re usually cheap space because they don’t perform very well.  They’re usually built into an attic truss over the garage, which gives them a lot of tricky and hard to insulate details like attic kneewalls and vaulted ceilings.  While a typical room might have two or three exterior surfaces (a ceiling or floor and one or two walls), bonus rooms often have five (ceiling, floor, and three walls).  This means that they have a lot more need for heating and cooling.  Unfortunately, it’s also common for bonus rooms to be located really far away from the heating and air conditioning system.  This means that they often don’t get as much air conditioning as they need and end up being uncomfortably hot or cold.  But if you try to zone them separately or to use a dedicated minisplit system, that adds expense.  So, if it were up to me, I’d skip the bonus room.

Things I’d definitely do…..

Heat pump water heaters:  These use one-third of the energy of a regular electric water heater, and pay for themselves without rebates in 3-5 years.  And they often come with rebates anyway.  You wouldn’t use electric baseboard heat in your house because it’s shockingly inefficient.  Why would you use it to heat your hot water?  I know, you read some online reviews, and they’re loud, they break and a repairman has to come, they can’t go in small spaces.  I want us to consider for a minute that perhaps online reviews don’t always lead us to make the best decisions.  They come with warranties.  Get a major brand and get it repaired if it breaks.  Something in your house is going to break.  It probably won’t be this, but if it is, it gets fixed.  They’re a little loud.  Less loud than your heating/cooling system (which is probably in the same room with it), and no one calls me to talk about how worried they are about that.  Unless it’s going in your bedroom closet, sound is probably a non-issue.  Fitting them into small spaces can be a problem (they’re tall) but you can duct them to neighboring spaces, so this problem is often solveable.  And it’s worth solving because it gives you FREE HUMIDIFICATION of the space it’s in.  If old-style electric water heaters were also working as dehumidifiers, I wouldn’t be able to pry them out of your cold, dead hands.  You should do everything you possibly can to make this technology work for your situation.

Fiberglass windows:  I didn’t do this in my own house because if you strictly run the numbers, the energy savings in our climate isn’t enough to justify the additional expense.  But if I had to do it over again, I’d choose them for the durability.  All day long.  Some things can transcend math, and this is one of them.

High efficiency filter and whole-house ventilation:  The more we learn about particulate matter and human health, the more we realize that particulate matter isn’t good for anyone.  It’s not just people with asthma and allergies who should be thinking about good filters – it’s everyone.  Particulate matter contributes to inflammation in the body and has been linked to heart attack and stroke risk.  I’d get a good filter (rated at least MERV 13), and I’d couple it with a strategy (air cycler, ERV, etc.) that guaranteed a minimum turnover of air through it even when the weather is mild and there’s little need for heating or air conditioning.  And because there are lots of other indoor air contaminants whose effects we don’t fully yet understand, I would definitely have whole-house ventilation.

Invest in a high-quality HVAC installer:  HVAC (heating, ventilating and air conditioning) is complicated.  It’s more complicated than most other parts of your home, and the larger and more complex your home is, the more complex your HVAC is.  One of the biggest mistakes I see people making (especially in high-end homes) is to treat the HVAC like a commodity and always using the lowest bidder.  This is one of the most complicated systems in your home, and it’s the one you (and probably your builder) know the least about.  Go with someone who has a long track record of successful installations in homes of the same type and size as yours.  Ask the higher bidders to take the time to explain to you why their proposed systems might add more value than a basic system.  Or if the same installer is offering cheaper and more expensive options, make sure you understand the benefits of the more expensive options before you turn them down. A lot of comfort complaints can be avoided (or at least fixed with some easy adjustment) if you hire the right HVAC installer to install the right system.

HERS rating:  This is a bit of an advertisement for our own business, but I wouldn’t do this work if I didn’t believe in it.  A HERS rating includes energy modeling, onsite verification, and performance testing of many important aspects of your home.  We almost always find multiple things that can easily be upgraded, changed, fixed, or adapted to give you better performance, durability, or comfort.  A home is the biggest investment most people make.  For a small fraction of the cost, it  makes sense to have a trained third party looking for these things.  It also gives you documentation of the home’s efficiency – a “miles per gallon” label that can be used to qualify it for above code programs,  energy efficient mortgages, and energy guarantee programs.  Having a rating can immediately make your home more affordable to own as well as boost the price should you ever need to sell it.

Copyright 2017.  Amy Musser