NextHaus Alliance Sustainable House Panel Q/A

Last night I participated in a panel discussion around building sustainable homes that was sponsored by NextHaus Alliance, the folks who are building our passive house. This is totally why I was included in the discussion. It makes sense to put your customers in front of a bunch of people and have them talk about why they selected your business, and why they think the thing you sell (sustainable homes) are a good idea :D.

I didn’t know what to expect and wanted to come prepared, so I wrote up detailed answers to the questions they were planning to ask the panelists. This was massive overkill for the situation, but most of it was rolling around my head anyway. Putting it on “paper” wasn’t hard, and I thought I would share it here. Obviously, this is a topic that I have strong feelings around.

I think the way we build homes in the US is shortsighted. Like a lot of things, we prioritize upfront cost and ignore the operational cost because there’s no incentive for the group making the thing to prioritize what is optimal in the long term. Even our current house, which is very nice by normal standards, is [relatively] poorly insulated, inefficient, and has a roof profile that makes it difficult to put a significant amount of PV on the building. Clearly that was on my mind when we designed the new house.


  1. What does it mean to have a sustainable, resilient and healthy home and why would someone want that?  
    • The real answer to the first part is that I don’t know yet. While our current home is a really nice house, it isn’t sustainable or healthy (in this sense).
    • Digging deeper, this is really three questions crammed together. So it’s probably important to break them apart at least a little because you can target each of these things discreetly.
      • Sustainability is about reducing the footprint of the home. Some of that happens in the design and build phases. Seal the house as tight as you can and choose electric everything. Even if your electricity isn’t clean right now most of the time it’s still cleaner to burn something at the power plant than your house because of the efficiencies involved. Long term, the grid should get cleaner, but even if it doesn’t we have options like community solar and panels (PV) on the house. With a tight house, and electric everything it’s much easier to move towards NET ZERO during the habitation phase; which is where most of the footprint comes from.
      • Looking at resiliency. Local energy generation with solar is half of how we solve this problem. Put as many panels on the house as you can, and you get electricity to run the things in the house. The other half is energy storage. Put in at least a day’s worth of use. If you can swing it, more is better. The price of LFP batteries is dropping rapidly. We recently purchased ~28kWh of storage for $7,000 before the 30% federal tax incentive. The total cost of the project, including inverters and installation should be around $10,000 after the federal tax credit. We’re planning to put in a lot more than that in this house (~71kWh). We’ve all had the power go out. The grid is fairly resilient in Chicago, but as the weather gets more erratic it’s likely that we’ll see an increase in outages. During the one big storm this winter, much of the area just west of Milwaukee lost power for 4-5 days when the temps were below 0F. When considering the cost of frozen pipes and alternate housing during those kinds of events, the additional cost of including resiliency into a house design is an easy sell.
      • Interestingly, making a house more sustainable can increase the challenge around keeping it healthy. Sealing the house tightly reduces air exchange. Good air exchange between the inside and outside of the house is essential in most cases to ensure that we’re not breathing pollution from cooking and breathing. The exception is when Canada is on fire, then we want the opposite. When your house is breezy, air exchange is a free but inconsistent feature. With a sealed house, installing an ERV helps with both things. We get intentional air exchange everywhere in a way that conserves energy. We’re planning to install an ERV that incorporates air quality sensors, both inside and outside the house. Which will allow it to react to poor air quality wherever it is. Which means we’re going to breathe fewer harmful particulates, and should get sick less frequently.
    • As to why someone would want those things.
      • Sustainability trades a marginal increase in build and design cost for a dramatic reduction in operating cost over the entire lifespan of the house. When you’re building a 100 year house, that seems like the obvious target.
      • Resiliency increases uptime and helps protect against adverse weather events. Losing power during heavy rain would suck for anyone with a basement.
      • A healthy sealed home improves your quality of life. There are fewer hot/cold pockets in the building, and the air quality is significantly improved.
  2. What’s the benefit to having NextHaus Alliance do this for you?
    • The main benefit for us is that they have experience building sustainable/passive homes, proven delivery for other clients, and shared accountability because of their business model. The architect isn’t chucking a hot potato at the builder and designer. They’ve been working together the whole time, and will continue to work together during the build process.
    • They have incentives to play nice together, and play nice with us. Vertical integration is beneficial here.
  3. What are some misconceptions about sustainable homes? 
    • The main one I’ve run across is that they have to be expensive.
      • While it is true, at least from what I’ve found, that there are upfront marginal costs associated with building more sustainable homes, the long term costs should be lower in almost every case. Looking at a recent e.g. coming from North Carolina, the state is trying to modernize their building code to make it more sustainable. The new code would raise the cost of the average house by ~$6,500, with an expected ROI in ~10 years. Maybe I’m out of touch, but having recently discovered how much kitchen faucets and toilets cost, $6,500 doesn’t seem like a lot of money in that context. (source)
      • Insulation and energy efficiency are great examples of this. It costs more to seal a house properly, but you make that back in energy cost savings. Energy costs aren’t going down, so this is likely to escalate in the future. For e.g. the price we pay per kWh went up 20% over the last few years. That 10 year ROI number is probably lower than 10 years when taking that trend into account.
      • Obviously, there’s a balance there in the cost/benefit mix. But the more expensive the home, the more it makes sense to drive towards higher levels of insulation and energy efficiency.
    • The other one I’ve seen is that it only makes sense for expensive houses. I do think the math is easier for larger budget builds. It is true that targeting sustainability costs more than ignoring it. Where it gets fuzzy is where the crossover point is, and I don’t have a great answer there.
      • So it doesn’t go unsaid, Passive House is more than $6,500. I don’t have great data around that. I’ve seen additional cost numbers as low as 2% and as high as 15%. The better numbers seem to be in the 3-5% range. Obviously where you’re starting from as a reference plays a role. The lower the standard is (i.e. containers are cheap), the more it will cost to get it to Passive is likely to be.
      • I’ve seen some Passive House projects that are $165 sq/ft, which is very affordable (source). This is higher than the average build price in most locations in the US, but not by much. Here again, we need to recognize that these are not substitutable goods. The additional cost nets a much better product.
  4. What is Passive House and is it a good idea to do? 
    • Passive House is a voluntary standard around efficiency that reduces the energy footprint of the building. The goal is a highly efficient low-energy building; mostly by insulating, removing thermal bridges, and sealing the house really well.
    • Conceptually, that seems like a no-brainer. Energy is expensive and has a footprint. The less you use, the smaller the footprint, the less you pay.
    • It’s very possible to build to the Passive standard without getting the certification. Whether the certification is important to you, which is what I think is what the “good idea” aspect of the question is getting at is a personal choice.
    • When we were trying to decide whether to pursue certification, we opted to do it. Some of that is because as a line item in the total project cost it wasn’t a big number. Some of it was that we were targeting that efficiency level anyway, so getting a testable artifact as an output made sense. It provides a tangible artifact that we got the thing we paid for. It’s an assurance for us and NextHaus indicating that they nailed – hopefully ;).


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