Show HN: Acre Designs (YC W16) - Zero-Energy Smarthomes as a Consumer Product

Re:Show HN: Acre Designs (YC W16) - Zero-Energy Smarthomes a... by krapht on Thursday February 11, 2016 @06:17PM (#11084104)

These are some seriously expensive houses. If net zero is about reducing total cost of ownership, these don't cut the mustard. I personally would be more interested in factory-built modular housing with the minimum of fancy gizmos - just the basics of high R-value insulation, good seals, appropriate placement of windows, and energy efficient HVAC. If net-zero is about reducing our carbon footprint, then I'd be buying a used house and doing some light renovations to make it more energy efficient.

You can get 80% of the way there by blowing foam into the walls, sealing leaks, investing in good windows, and making sure your HVAC system is appropriately sized and used only when needed.

Disclaimer: I used to work on this: http://ecomod.unm.edu/ so I might be somewhat cynical.

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Re:Show HN: Acre Designs (YC W16) - Zero-Energy Smarthomes a... by andrewksu on Thursday February 11, 2016 @06:43PM (#11084249)

We'll get there next year, but to take the price leap, we have some new tech to get ready for market.

CA has Title 24, which mandates net zero for new homes, so that is the long term focus.

Check out the home we just completed for $145K, looks great, great performance and very comfortable. It's just hard to do at scale with out a bit of a war chest.

As you know, blowing foam, sealing leaks, upgrading HVAC, and good windows will run most folks close to $60-$100k to upgrade. That will still leave it fairly leaky, have an un-insulated foundation and be an older structure. Wish there was an easier solution to upgrading existing homes, but that is a tough business.

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Re:Show HN: Acre Designs (YC W16) - Zero-Energy Smarthomes a... by krapht on Friday February 12, 2016 @12:50AM (#11085563)

Sure, renovated old stock isn't airtight, but nobody needs that. I've been in some passive houses - net zero by virtue of the fact that they ventilate the bare minimum of air. Soon as you get some nasty furniture outgassing tons of VOC, ugh! Living quality goes waaaay down. Headache central. Same thing if you put a lot of people in one room - the bare minimum ventilation will cause CO2 concentrations to go up and again, headaches, dizziness, etc.

I don't believe in local stick build kits for your business. Every customer is going to consider the total cost of labor for your houses. I don't know if it's possible, but I hope you consider partnering with a modular home builder with an existing sales network. Clayton Homes or whatever. Then you only need to build to one standard (Fed DOT... I could be wrong though, never looked into the regulations too deeply) and you can leverage their sales and financing force.

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Re:Show HN: Acre Designs (YC W16) - Zero-Energy Smarthomes a... by newman314 on Thursday February 11, 2016 @09:26PM (#11084918)

Question: what do you think of this?

https://www.fortis.edu/blog/skilled-trades/wasted-attic-heat...

I wonder about the option of scavenging heat in the attic during the winter into the rest of the house (through filters) or if it's just a waste of effort.

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Re:Show HN: Acre Designs (YC W16) - Zero-Energy Smarthomes a... by krapht on Thursday February 11, 2016 @11:04PM (#11085216)

These things work, but ultimately never turn out to be more cost-effective than sealing your house up better and adding more insulation. You will only see them in high-end commercial construction. The technical term for it is zone heating and cooling, although what is described in that paper is a little smarter than what is typically done.

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Re:Show HN: Acre Designs (YC W16) - Zero-Energy Smarthomes a... by andrewksu on Friday February 12, 2016 @12:09AM (#11085447)

Agree, there would only a handful of days where the combo of temps and solar gain would provide the right boost.

PCM's (phase change materials) might work better in this application. However, air tightness and a consistent insulation layer is best.

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Re:Show HN: Acre Designs (YC W16) - Zero-Energy Smarthomes a... by newman314 on Friday February 12, 2016 @01:39PM (#11089365)

Interesting. I read up more on PCMs.

The challenge I've had is keeping the house warm in the winter where internal temps will drop down to the 50s without the heater on. During the summer, I rarely have to turn on the AC even when it's a 100+ day so there's plenty of insulation. I suspect much of the heat loss is due to the giant windows that I have even though they are double pane.

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Re:Show HN: Acre Designs (YC W16) - Zero-Energy Smarthomes a... by dangravell on Friday February 12, 2016 @07:55AM (#11086850)

PCMs are being used in the domestic market for DHW (domestic hot water) now. Interesting developments - the batteries tend to leak much less energy than standard water based hot water cylinders.

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