On the Passive House in the Real World (with Mike Duclos) discussion board… 


  • Homeowners looking to incorporate Passive House principles in existing buildings should consider getting a home energy audit. Still, after a home is built, serious energy reductions (say 50% to 90%) become very expensive.
  • Attic insulation adjustments and window treatments offer more immediate fixes toward energy efficiency.
  • Electricity is typically our dirtiest fuel, so savings there help a great deal.
  • Current building codes can prove inhibitive to homeowners looking to renovate or upgrade their homes.

Student 1: “Mike,

This course is giving great tips on how to design, build, and test various portions of a house properly from the ground up to achieve PH standards. Can you comment on what the biggest “bang-for-your-buck” improvements might be for renovating/remodeling a typical non-passively designed house? Aside from the commonly suggested items – new windows, more attic insulation, newer mechanicals, etc – I’m wondering what else might be commonly done to bring conventional building details closer to PH principles.

I’m thinking about my own house (~20 years old, 2 story colonial, standard build details for Buffalo, NY area) and the list of things to check is getting longer and longer! This may not be completely on-point for this course, but I’m sure there are things that can be done to help a “non-passive house in the real world “perform better.”


Mike Duclos: “Student 1, I think your question is very on point: you are trying to improve an existing home, which will probably be standing 100 years from now, so long lasting improvements you make today that save 7 gallons of fuel oil or 10 therms of gas will save 100 times that in the long run– definitely high leverage.

You’re near Buffalo, and so 6500-7000 HDD 65F qualifies you as a Cold Climate!

I don’t know the design of your home, but if you have an attic, I’d guess the best place to start is to pull up or remove the insulation and air seal the attic floor.

In the existing building stock from 25% to 30% or so of the annual heating bill is air infiltration– convection washing the heat (and moisture) out of the home in the winter.
This is probably the single biggest ROI measure for most homes. Then, fill the attic with maybe 16” of cellulose, which is much more effective than fiberglass batts, although you can realize an improvement by blowing cellulose on top of batts, if you have strapping between the ceiling joists and drywall, that gap won’t get filled and unless you do something to prevent horizontal convection from pumping heat out the top plate, it will be less effective than all cellulose.

But in NY state, I think you have access to weatherization programs from NYSERDA, no?

Have a look at NYSERDA NY’s Residents and Homeowners guide and NYSERDA Project information.

I think the home energy assessment would be a great way to get an opinion of the high leverage areas in your home and it looks like it could be low price or free.

In MASS we have MassSave (which provide energy audits). I had a home energy assessment, and they swapped out the bulbs for LEDs, (this can be a major savings that will reduce CO2 for decades to come) offered me low flow shower heads, (I already had some at 1.5 GPM I quite liked) programmable thermostats, evaluated the insulation and air sealing, and offered free air sealing and very low cost insulation via cost sharing. I’ve heard NYSERDA programs are pretty good, but I’ve no first hand experience.

If you haven’t yet done the Lights and Appliances homework this can be an eye opener… Electricity is typically our dirtiest fuel, so savings there help a great deal.

 Tweet: “Electricity is typically our dirtiest fuel, so savings there help a great deal…” #PassiveHouse @nesea_org @HeatSpring

Turning stuff off, unplugging stuff (maybe that ‘beer fridge’ in the basement burning 700 KWHR/Yr ?) is a very low cost improvement.

Another reasonably high leverage area is the rim joist (foundation to wall intersection) air sealing and insulating- this is a high ROI measure in many homes.

Much depends on the particulars of your home, the home energy assessment will hopefully point out the key areas.

Bottom line: after the home is built, serious energy reductions (say 50% to 90%) are expensive, the ship has sailed. In my opinion, current building codes are doing society a disservice, this is why I refuse to work on buildings that are not what the MA new homes program classifies as Tier III (and for which they give a $7000 incentive: R10 slab, R20 foundation walls, R40 above grade walls, R60 roof, R5 glazing, 1 ACH 50 Pa.) Much less than that is just making another candidate for a DER and is contributing to the problem, not to the solution. What do you think?”


Student 2: “A couple of things to your last point about Tier 111 homes:
I absolutely agree with you on the existing building codes. Most codes today and those of the past, when present at all, were not based on sound building principals and certainly did not reflect responsible energy consumption awareness. But the past is the past, which leads me to my second point. With the substantial herd of ‘energy pigs’ that make up the housing stock of this country, I see a great opportunity for net energy reduction with DERs in these structures. PH or ‘Pretty Good Houses’ moving forward and DERs with the old together with updated building codes that reflect a responsibility to the long term safety of building occupants and society/environment in general.

I’m curious about the comment:
‘I refuse to work on buildings that are not what the MA new homes program classifies as Tier III’. I’m assuming you are referring to homes new or old that can’t be brought to this level and not any old leaky home that is not at this level but looking to be improved?”


Mike Duclos: “Student 2, I should have written ‘new homes. ‘ I consider a new home that is insufficiently insulated and air sealed to be a very large lost opportunity, it is so easy to do well, and costs so little extra (and could cost less with a ‘systems approach’ to thinking as we’ll discuss in week 4) it’s really sad to see Business As Usual. A Carbon Tax could change that.

It is a real challenge, and very expensive to take existing homes to this level of performance. When surfaces are exposed for other reasons (e.g. residing, etc.) I encourage people to do as much as they can to upgrade, since that is the last opportunity that building will have, until the siding needs to be replaced again.

Generally siding and window upgrades should be done together, but I saw the results of a remarkable contest the PHI sponsored at the PH Conf in Leipzig this year, the goal was ‘re-positionable windows,’ since there are building physics reasons you might want the upgraded windows installed prior to a facade upgrade, if you can’t do both at the same time (for example because you could not afford to do both simultaneously.)

One excellent resource that came from the National Grid DER Pilot, is the DER guide that illustrates some many carefully thought out details.”

What do you think about bringing existing homes to high levels of performance? Tell us about your experiences in the comments!

Passive House in the Real World is developed as a part of the NESEA: BuildingEnergy Masters Series.


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About Mike Duclos – Principal, DEAP Energy Group, LLC

Mike Duclos is a principal and founder of The DEAP Energy Group, LLC, a consultancy providing a wide variety of Deep Energy Retrofit, Zero Net Energy and Passive House related consulting services. Mike was an energy consultant on the Transformations, Inc. Zero Energy Challenge entry, and has worked on a variety of Zero Net Energy, DER and Passive House projects, including two National Grid DER projects which qualified for the ACI Thousand Homes Challenge, Option B, and a feasibility study of a retrofit to the Passive House new home performance standard. Mike is a HERS Rater with Mass. New Homes With ENERGY STAR program, a Building Science Certified Infrared Thermographer, a Certified Passive House Consultant who certified the second Passive House in Massachusetts, holds a BS in Electrical Engineering from UMass Lowell, and two patents.

Mike is teaching: