HVAC Sizing for Eco-Panels Homes

If you really look at the philosophy behind building a super-energy efficient home, it's that the interior spaces are very much protected from outside conditions, and it only takes a small amount of energy to affect change to the interior environment.  "Heat it with a match-stick, cool it with an ice-cube" would be our mantra if we had one.  And what's better is that when you have a super insulated structure that can be affected by small amounts of energy, then you can realize savings that a stick framed home could only dream of.  We have homes set on concrete slabs and they are able to realize and leverage the passive cooling energy of that slab.  And we have tiny homes that use incandescent lightbulbs to provide 100% of the heat for a small home when it is below zero celsius outside.  We provided the roof and walls of a 15,000 square foot retail space that is cooled in the summer largely by its concrete slab (HVAC is still needed for dehumidifying) and in the winter the heat is provided by its retail lighting.

REMEMBER- the energy associated with the heating and cooling of your home represents the single largest expense of living in that home (outside of your mortgage), typically accounting for 40-60% of your total energy bill (water heating is usually about 20%, the rest is known as "plug load").  In fact, the heating and cooling of buildings is about the largest singe use of energy in the United States according to the USEIA.  By significantly reducing your energy consumption associated with the heating and cooling of your home, we can help you save real money over the life of your home - and this saved money goes straight to your pocket - not the energy company!

Most homes will have a more convential HVAC system for heating and cooling the home, and here is where you need to be careful.  DO NOT LET YOUR HVAC GUY USE A TRADITIONAL "RULE OF THUMB" that might mean he is going to size the HVAC based on 1 ton for every 600 or 700 square feet of home.  Now local building codes very often require a "Manual J" calculation which takes a more in-depth look at the construction, fenestration and orientation of your home for HVAC sizing, and even this more advanced method almost always gets it wrong with our panels.  Through experience, we have found that generally speaking a home of approx 4,500 sqft in size may need a 2.5 ton HVAC system.  Buy a variable speed HVAC system if you can - these used to not exist but with the increased presence of mini-splits we are seeing it more and more.  A 3,500 to 4,000 sqft home might need a 2 ton system.  A home 1,500 to 2,500 sqft can typically get by with a 1.5 ton system.  So if we had to say we had a rule of thumb, it would be approximately 1 ton of HVAC for every 1,500 to 2,000 sqft of house.  Always use at least Energy Star rated windows (and the rating needs to be appropriate for your climate zone), and Cardinal Glass is also a great choice (odds are your window mfgr offers it).  We do like mini-split systems as these can be great for smaller homes (they have been long used in Europe and Asia where smaller homes are more the norm).

ASHRAE tells us that an HVAC system needs to run for at least 15 minutes or so before it starts to achieve optimal operating efficiency, and in a super-insulated home we have heard past clients of ours brag that "we know our home is super-energy efficient because the air conditioning only runs for 5 or 6 minutes at a time before it turns back off".  We slap our foreheads in frustration because we know that the HVAC company sold them an oversized unit - sometimes more interested in a bigger sale than a "right-sized" sale.  Their unit may indeed be cooling the house, but it is not "conditioning" the house, which is eliminating the high humidity levels that any summer months may realize.  And all of the short-term cycling of the equipment will certainly shorten its useful life, again increasing your long term operating costs.  In reality you want a system that will run "low and slow" in the background, cooling and dehumidifying but at the same time using a lower amount of energy - this is why a variable speed system like a mini-split or one of the new TRANE variable speed units is attractive to us - they are made to run longer on lower power.  You don't want it to run all the time, for sure, but I think 30-40 minutes or so is just fine.

HERE is a nice article on "right-sizing" an HVAC system for a super-insulated home from a blog that we appreciate (and we think they give great advice most of the time).  If your HVAC contractor is not familiar with this sizing concept and always thinks that "bigger is better" then RUN AWAY - they are not the company for you.

Nice Testimonial from South Texas - with Pictures

But south of San Antonio Texas the attempt at extreme energy efficiency at little to no extra cost is alive and well!  We received some recent feedback from a DIY client and I am re-posting below.  This guy is a CPA so he did the math, and knew it made sense.  With a concrete slab floor and our panels wrapping the envelope he'll have constant natural cooling from the earth.  We were very happy to see he did not go with one of those too expensive geo-thermal or "water furnace" systems or radiant slab - when using our system you simply don't need expensive forms of heating or cooling.  "Cool it with an ice-cube, heat it with a match-stick."

See below testimonial & attached nice photos (exterior is Huber ZIP System siding).


From: Daryl H.
Sent: Friday, February 10, 2017 8:31 AM
To: Charles Leahy < This e-mail address is being protected from spambots. You need JavaScript enabled to view it >
Subject: RE: How is it going?

The only thing I did was do a lot of reading on the internet and in the forums. A lot of folks spoke of their performance from their sip homes. One factor was thermal bridging and on my last house from experience fiberglass just doesn't cover all the voids. Also corners were another void which was hard to insulate especially the way framers tend to build them. Your corners is what caught my attention. I did put the pencil to it to figure a studded house with polyurethane foam, zip panel and foam on the outside and there really wasn't any savings. Plus having to watch all the trades. I have a friend who has been watching what I'm doing and has been surprised at how sturdy the walls are. He wanted me to build with stick but I planned this way too long to deviate. My ex-wife cousins husband  had to rebuild their sausage plant freezer and it's just all foam with steel frame for the door. So it makes sense. I will say since this was my first sip project I did shop around especially since I was unfamiliar with all the technical details. Some made their products sound really good but then couldn't explain what they needed. Your company was very helpful throughout and as I've always said service is the key. Next time or if someone wants a recommendation I would have to refer them to ecopanels. Save yourself time and the headache and just go directly to y'all. Sorry got long winded. I'll keep you updated. My Corinthian columns came in and my framer is freaking out. They weigh a lot. He will get it. The picture is from the other day. I believe Tuesday.

On Feb 9, 2017 7:14 PM, "Charles Leahy" < This e-mail address is being protected from spambots. You need JavaScript enabled to view it > wrote:

Hello Daryl!

My apologies for the delayed response.  Generally we work on air sealing between the plates before the panels are set – we try to discuss this in the “Quick Start” guide in our Assembly Manual that you have.  But there is no reason you can’t start now – by all means not too late.  On one of the tightest homes we’ve ever seen the guy simply walked around with a caulk gun and sealed at the bottom of the panels and the base plate – and this was after he had already put some construction adhesive under the base plate.

You do not need to worry about protecting the underside of the panels.  As long as those skins are not touching the concrete – and instead resting on the treated plate – you’re good.

One thing you can easily do is take the Huber ZIP tape and seal the joint between the panel and the treated base plate.

I am not familiar with a “shroud” like product that would cover down from the panel to the cement – I’ve not seen that before.  Interesting as long as there is no trapped air.

THIS is a company that we respect very much -  Check out their products – they are out of Europe originally but have distributors here and one of our top builders uses them religiously, including their tapes that require priming with adhesive before applying – maybe talking about the same thing?  But I do not know why you would put a barrier over concrete – I’ve not heard of that before.

Question for you – as a CPA – did you do any sort of long range analysis for your home’s performance using our panels vs. if it was stick framed?  I’m just curious.



From: Daryl H.
Sent: Friday, February 3, 2017 8:31 AM
To: Charles Leahy < This e-mail address is being protected from spambots. You need JavaScript enabled to view it >
Subject: Re: How is it going?

The panels are up and the framers are on the ceiling joists. This weekend I hope to finish sealing the panels. The cutouts for the porch joists seam to be working out well. I couldn't find the 2x12 hoist hangers so we made some from 1 1/2" angle iron. The framers complained a little about how they thought this took more time but I figured it shaved off time and even more time for insulating. They may be fast but not that fast. I have been watching other houses go up and none have gone this fast. We had a load of lumber scheduled shortly after the the panels arrived so we convinced them to unload the panels. The framers were going to unload the panels but after seeing the load they had second thoughts. I've attached a few pictures for now I'll send more later. Just wanted to say out of the panel companies I talked to and considered, your group was the most helpful and responsive even when the panels got reversed. Still not sure why my son and the framers went ahead and did that even though they saw it was wrong. That's what I get for leaving 1 hour to get foam. In that 1 hour they probably installed 35 feet of panels. It worked out. Will send more later. Thanks

On Feb 3, 2017 6:15 AM, "Charles Leahy" < This e-mail address is being protected from spambots. You need JavaScript enabled to view it > wrote:

Good morning Daryl,

I have not heard how it went with your panels – I hope well and you are happy – that is certainly our intent.  Do you have any photos you can share?  I’d love to hear more about your experience – if it is good maybe we could construct a story and feature it on our facebook page.


Charles Leahy


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Quality Check in our factory prior to shipment - note beam pockets at exterior corners pre-formed in factory for quick mounting on jobsite.

Quality check of custom home in Eco-Panels factoryCustom Home Quality Check Prior to Shipment

Job-site photos from client.  It took him about one day to erect the wall panels - said it took place mostly on their Tuesday and partly on Wednesday.

Numerous Wildfires in Western NC, now TN

>>> I wrote this article only about three weeks before the firestorms ripped through our nearby community of Gatlinburg, TN, just over an hour from where I live.  Our thoughts and prayers go out to all those affected by this tragedy.  <<<

While I grew up in North Carolina, spending many summers hiking & camping in the beautiful Blue Ridge Mountains, later in life I moved to California and worked in the Hi-Tech industry.  It was in California that I learned about wildfires - occasionally being around them first-hand - and unfortunately for them they are not uncommon due to their dry environment.  Now after having returned to North Carolina I am in those beautiful mountains once again - and I am horrified to see that things have changed so much that now I am seeing wildfires every year in mountains that may not have known wildfires for a thousand years.  As far as we know it was always too wet, too green, too lush with green foliage to allow any fires to be sustained - in fact there was a time not too long ago that the "southern blue ridge escarpment" received the 2nd highest amount of rainfall in the country, second only to Washington state's Olympic peninsula.  Not any more, that's for sure.  All week the air in Asheville has been grey and smokey - burning your lungs if you breath too much.  Very sad.

But anyway - the point of my posting - is we are receiving much interest lately from all parts of the country regarding our flame retardant foam.  EPS foam panels or SIPs have the foam core melt at very low temperatures - this can negate their ability to provide structural support even if flames are not touching a building.  The foam core can melt and the building can collapse - simple as that.  Our closed cell polyurethane foam core will NEVER melt - take a look at the two video links below - and if we or your home uses fire resistant siding materials - then - well, we would expect them to perform much better than traditional methods.  I think you would be much better off if a forest fire or wild fire gets close to your home - or even if you have a kitchen fire inside your home (those can achieve 1,700 degrees just right over the stove) your home should be much better off.  And we have seen some insurance companies offer lower homeowner rates in part because of this (they rate it as "Superior Construction" - USAA and Allstate are two of them).

Please see these video links!

Hurricane Matthew Aftermath in NC

This time last week our state of North Carolina was still feeling the brunt of Hurricane Matthew.  Our thoughts and prayers go out to all those along the east coast from Florida through the Carolinas affected by Hurricane Matthew - in fact I had seven family members affected by the storm and several of them are still dealing with the aftermath.  I have sent questions out to several past clients that we have in those affected regions and have received feedback which I include below - and I also wanted to remind people of previous blog postings where the Federal Emergency Management Agency (FEMA) notes that the ONLY insulation approved for construction in flood prone regions - and those covered by the National Flood Insurance Program - is closed cell polyurethane insulation as used by Eco-Panels.  Note most insulation sold on the market today - from open cell foams like Icynene(R) to fiberglass or cellulose insulation or even most EPS panels sold on the market do NOT meet the definition of closed cell insulation and therefore do not perform well in these conditions.

Here are a two testimonials we have received so far:

Chris from Nags Head, NC -  “the winds got up to 100 mph but everything was just fine – solid & secure!”

Tim from West End (Moore County, NC) - Thanks for thinking about us. We had a lot of rain and wind but no flooding or damage. I do have to say that I noticed how quiet it was inside the house during the storm.  There was no wind whistling around the windows and doors because there are no cracks and crevices, and I hardly heard the rain hitting the house.  It’s been over five years since we built and I have to say using Eco-Panels was a decision I never regretted.

Regarding building along the coast or in flood prone areas:

Fire Retardant Foam Insulation - Videos

I used to live in California - working a good portion of my life in the hi-tech industry in Silicon Valley - and it pains me to see the raging fires in that beautiful state that seem to arrive earlier each year, taking a larger and larger toll on the communities who lie in their path.  When we started Eco-Panels, determined to create the strongest and most energy efficient building envelopes in the world, safety was always at the forefront of conversations.  STRUCTURE is always our primary concern, with thermal efficiency coming in at a close second.  And it amazes me as we consider the safety of building envelopes that probably 90% of the structural insulated panel (SIP) industry that we operate in is comprised of manufacturers using polystyrene or EPS foam insulation.  This is like Styrofoam(R), the small white compressed beads compressed together for a coffee cup or food packaging.  Actually you don't see styrofoam(R) food packaging much anymore - communities all across the country are banning it because it is difficult to recycle and not good for the environment.  But the point I am getting to is that while EPS foam may be a mediocre insulator for building materials (insulation value only slightly better than fiberglass) it reacts terribly to fire, either igniting outright or melting or vaporizing due to the presence of often very toxic additives like the neurotoxin and bio-accumulating brominated flame retardants.  Remember, a structural insulated panel acts like an I-Beam, with the panel "skins" acting as the flanges of the I-Beam and the foam core is its web.  Just as if you took away the middle member of an I-Beam and the beam collapses, when a STRUCTURAL panel loses its foam core it also collapses, allowing for a more complete destruction of a building than might otherwise occur.  A fire captain touring our factory once told me that temperatures from a small kitchen fire can reach more than 1700 degrees, and EPS insulation starts to melt/deform at less than 200 degrees, and sheetrock and OSB skin offers very little insulation against these high temperatures.  This is why it is virtually impossible to get insurance on a building made out of polystyrene (EPS) panels in the United Kingdom - while still legal by building code the insurance industry does not like to insure structures made from this material - (see discussion & results of 10 year case study elsewhere on our website).

The proprietary foam blend used by Eco-Panels will NEVER melt.  Ever.  Known as a "thermoset" foam, if it comes in contact with flame it will char, thereby protecting itself.  And, well, if we use a flame resistant siding "skin" on the panel it can create a wonderful barrier to flame.  Take a look at these couple of videos I recently posted  - I still need to get them directly hosted by our website - but I hope you will be impressed.  If it stops this kind of heat from a torch - I don't think you'll have much problem at all with a hot summer day!  NO OTHER STRUCTURAL INSULATED PANEL MANUFACTURER IN THE COUNTRY USES THIS SAME FOAM BLEND - ONLY ECO-PANELS.

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