Hacker News Reader

Comment by droithomme | Hacker News Reader

Passive solar for air and water temperatures is the way to design it into new homes. Cool in summer, warm in winter. Few to no moving parts or electricity needed. Little to ever replace. Anathema though to fancy solutions favored by VCs like photoelectric utilizing the strip-mining of millions of hectares of arable land, followed by toxic run-off, to produce panels and batteries.

For retrofits of existing homes, geothermal whenever possible for upgrading central climate control when present. Current professional installers though are generally incompetent and price-gouge. Sufficiently motivated hackers can easily DIY.

View on HN

Passive design can be climate specific, but I agree, it needs to be built into new designs. The problem that I'm seeing is that "no one" cares: developers will build houses with gorgeous kitchens/bedrooms/living rooms, but the HVAC stem will be bottom-shelf equipment with flex duct run all over the place (and pinched in a few other places). Because no one sees it, nor thinks to question it. We really need to figure out how to make it desirable and something people demand. Maybe that's raising electrical rates or taxing antiquated system design? Some form of hitting a wallet?

I like what you're thinking about geothermal; it sparked a few thoughts, though: Geothermal is expensive because of labor, not necessarily price gouging. Most installers (in my area) put a 10% mark up on everything: finding competent installers is harder and harder these days, so you're paying more and more. HVAC techs can make six figures if they have the experience and aren't afraid to negotiate. Unless, of course, they ARE price gouging, which happens, especially if they're already busy (which has been the case for the past three years).

The technology is solid, though to be frank, a high efficiency air-to-air heat pump will be comparable to geothermal, depending on the climate zone. If we can figure out a cost-effective way to replace gas-fired heat in northern climates with something more eco friendly (and consumer friendly), progress would be made.

Charging higher prices when demand is high is not gouging.

If people are making 200k At faang what’s wrong with tradespeople making 100k when their skills are also in demand.

Everybody who supplies or resells equipment puts a mark up on it because there is some cost for them to select it, procure it, store it, transport it, finance it, etc.

In construction price gouging is often less about the rate than less ethical charges.

At least in the EU the "no one cares" is changing. Member states need to have legislation in place that means from 2020 all new builds are "nearly carbon zero" (unfortunately left to interpretation by country). In my country that means homes have insulation and heating requirements on par with Passive House standards, as well as the majority of their energy coming from renewable sources.

Solar hot water heating works really well in the northern US. It’s an odd tradeoff as you get less energy so you need to scale up, but you also use the system more days out of the year. You do want a large thermal mass which can be difficult to add to an existing home.

> The problem that I'm seeing is that "no one" cares

It even more fundamental: no one knows about passive buildings. With homes, it's like we are still in the 50s with gas guzzling cars. That required a major oil shock to force a shift in fuel economy. No such impetus yet for homes, but when it comes, hopefully we have figured out a way to retrofit our housing stock cost effectively.

> The problem that I'm seeing is that "no one" cares... Because no one sees it, nor thinks to question it.

Put another way: the cost of operations isn't factored into the sales price. The builders don't have exposure to how much the buyer will pay to heat the home, so there's no reason to do extra work to insulate or seal better.

There are starting to be home efficiency standards that are being considered in the real estate markets (things like LEED certification for homes), but you're right, people are more likely to buy based on the look of the kitchen than the winter heating bill.

I've been trying to think if there's a financialization play possible... something like monetizing the downstream efficiency savings to incentivize the upfront work. The solar PPA model has been the solar company's monthly bill becomes your new electricity bill, and (ideally) paying off the solar installation monthly over 20 years was still cheaper than paying for non-solar electricity during that time. I've been wondering if something similar can be done for home efficiency upgrades.

"Geothermal is expensive because of labor, not necessarily price gouging."

In my experience, this is true. Comparing the electric heat system from one HVAC contractor to the ground source system I went with, there are a few expenses that are unique to ground source that start to add up. (USA - 2016)

$3,000 for the man and machine to dig the trenches and fill them back in.

Unknown - 2 days with a handful of laborers and 2,400 feet of pipe to lay and fuse together.

1/2 day to fill and purge the air from the pipes.

The equipment is more for sure, but I don't know an exact figure, but multiple thousands.

Overall, the 2 bids were about $15,000 different. Tax credits and even a rebate from the utility co-op made it close enough to a wash that I went with ground source and have been very happy.

When people ask about my monthly bill, the next question is "Why doesn't everyone do that?" I think many people don't care enough to deal with the sticker shock of a more expensive system. Another big reason is the amount of land required for horizontal trenching (there are other options, but this is generally the least expensive).

I also agree that if your climate is mild enough to use an air source pump, go for it. They don't quite cut it where I'm at (USA, just shy of Canada).

THe biggest thing you can do is properly insulate.

100-200mm of insulation on the outside of the house/loft/underfloor and triple glazing

The biggest "passive" design from my understanding is a few deciduous trees. In the summer, the leaves block out the sun, but in the winter, the leaves fall off and the sun directly heats the home.

That's fine when you live in a house. Not so relevant when you live 20 storeys up. I feel like way too much time and effort goes into improving single family houses, as opposed to larger multi-family buildings. They could be built to be much more efficient and just as comfortable. But alas.

One problem is that fire prevention and safety has trumped energy efficiency.

Can I open my window more than 4” no, someone could fall out.

Can we prop our doors open to get a draft? No.

The reduced external surface area to volume ratio really improves efficiency though.

Bigger factors in passive house design are siting and orientation, building envelope air sealing, continuous insulation, and correct window placement and shading - usually with purpose designed shade structures - not trees.

It's not that trees can't provide the shade, but they take a while to grow enough to achieve the immediate effect of an awning. If you have a mature tree on a site, however, you could design a house that takes advantage of the shade it already provides.

By geothermal you mean a ground-source heat pump? What is the bare minimum cost of the materials & digging & installation?

It’s always a lot. Can be kinda low if you’re allowed to do open loop water and a high water table but they’re often banned.

Passive homes are great, but they aren't mutually exclusive with PV. In fact, passive homes typically use PV for powering systems that require electricity to run.

Reply on news.ycombinator.com