The brits aren't nearly as confident about wind and waves as you. The govt is proposing higher electric rates to guarantee a return for generating companies that build nuclear power plants. (!?) http://www.dailymail.co.uk/news/article-2148381/Electricity-bills-200-pay-nuclear-dream-Families-hit-ensure-profits-firms-build-reactors-wind-farms.html?ito=feeds-newsxml Seems the UK grid faces substantial shortfall as aging nukes and coal plants go offline. Say what you will about pellet stoves. They are blackout resistant.

They are actually betting on the wind and waves, as well as the sun. In a country of very deep cuts, renewables promotion has been surprisingly stable. They figure that they have the resource and no one really wants to buy gas from the Russians.

No criticism implied. Almost alone in the world, the UK has reduced carbon emissions.
but I doubt that the govt would say they need nukes to continue progress on that front if there was a more palatable answer. As for renewables promotion, my sense is that the Brits use more sticks than carrots compared to the Germans or even the US. But I don't know that for a fact. My involvement in this thread is simply to say that no one here to date knows enough about hvac in the UK to offer advice without qualification.

Posted By toddm on 29 May 2012 07:34 PM
The brits aren't nearly as confident about wind and waves as you. The govt is proposing higher electric rates to guarantee a return for generating companies that build nuclear power plants. (!?) http://www.dailymail.co.uk/news/article-2148381/Electricity-bills-200-pay-nuclear-dream-Families-hit-ensure-profits-firms-build-reactors-wind-farms.html?ito=feeds-newsxml Seems the UK grid faces substantial shortfall as aging nukes and coal plants go offline. Say what you will about pellet stoves. They are blackout resistant.

He wasn't talking about point-source heating with a manual-feed pellet stove, or anything like it.  He was talking about high efficiency hydronic-output pellet BOILERS with a thermal buffer tank and radiant floors, which are not remotely blackout proof. No power, no pump, no blower to drive the high-efficiency heat exchanger, etc.

Somehow a slowly increasing £97-£200 (17%-35%) rise in annual costs over the next decade or so to pay for a greener grid seems like a bargain compared to what the Germans have been paying over the past decade.  I'm currently paying nearly the same rate per kwh as the lower, official estimate your referenced article is projecting for the 2026-2030 time frame, and I expect to be paying more the higher estimate by 2020, let alone 2030.  I'm not alarmed, and neither should the UK be- the cost of the grid upgrade is affordable, if annoying to those accustomed to 11p/kwh (€0.14, $0.17 USD) electricity.  I'll bet they'd rather trade motor-fuel prices with us than power prices. :-)  German residential rates are currently averaging €0.25 ($0.31 USD, largely driven by generous feed-in tarriffs on solar PV) which is already WAY more than the 2026-2030 projected rate for the UK in that article.

Sure, the UK is a low-rent slum compared to Germany, but the average German is still paying a bigger share of household income for energy than the average Brit, and that will continue to be the case in 2030, all hand-wringing aside.  The Brits are doing it on the cheap, taking their time relative to the Germans, and it isn't going to break the bank.

As with most projections like that the actual rise in power costs are likely to come in lower than expected:  Once fuel-free grid sources are built, the marginal cost per kwh is less than the fuel cost for fossil sources, putting a damper on peak rates.  If they invest a fraction of the capital-improvement budget in smart-grids, people/businesses will sign up for demand-response service (clearly most residences would to save on per-kwh rate) which would cut peak-generation costs almost entirely. Even thought the lifecycle kwh of wind power is higher than a coal-fired grid average, it flattens the rate rather than increases it in most cases.  The price of atmospheric carbon under the EU plan determines what is ultimately cost-effective.  If the Germans are willing to take a further price hike to shut down nukes (and they are indeed willing, despite some Nein-sayers, given their ambitious renewables program), I expect the average Brit may be willing to take the modest hit on rates to move away from coal (and stop shipping all that "free" sulfur to Scandanavia.)

Blackout resistant would hvac that is easily maintained in power outages, as in springing $130 for one of these: http://www.walmart.com/ip/CyberPower-1200VA-720W-Battery-Backup-UPS/10250448?findingMethod=rr (Tapped out grids typically would have time of day outages) Perhaps radiant is standard issue in the UK because it takes very little current to turn two pumps -- or no current at all if the OP wants radiators and a plain ole wood stove boiler designed to heat some or all by thermosiphon. British boiler design is vented -- straight out of the 1950s. That said, the boys down at the Cock and Bull, if the conversation turned to the Yank custom of pressurized boilers, would exclaim "What ho! A potential bomb in the basement!" Culture is best understood from the inside looking out.

I am dealing with a lot of Brits and other Europeans partly because i buy controls and other products directly from there and I talk to heating guys there almost daily. The Brits are late comers to green energy compared to the Germans and the current FIT pricing in Germany is around $.30/kwh, just over half of the new, reduced, FIT pricing available here in Ontario. The current UK rates are similar to Germany.

There is no more subsidy for residential solar thermal in Germany and yet the sales have taken a big upswing in the last year.


You have to remember what traditional housing stock is like in much of the UK, low ceilings, often no basements, small rooms compared to here and the majority of houses didn't even have central heat until the 60's. There are many POU gas fires that took the place of coal ones. There was no room for noisy ductwork that would move the coal dust all over the place. Rads were the way to go and compact boilers are the norm.

Radiant is definitely NOT standard issue in the UK (or anywhere else.) Hydronic radiators are the UK standard (used to be small high-temp types in antique home retrofits, but low temp flat panel versions are standard for new construction and retrofits that can accommodate them.)

The UK is a a first world country, with a more reliable power grid than the US. Spending money to ensure that a near-zero heat loss home would require a heating system capable of riding out a blackout for hours or days would be silly. Most homes in the UK have 4-5x or more the projected heat loss of anything that could be described in any way as "near Passivhouse", and have no such provisions, and rightly so! Even in winter there will be cooling loads for a near-passivehouse, and those are loads that can be managed manually by opening windows when it overheats. You COULD build for an Armageddon scenario, but why would you, especially when you'd coast through it in higher comfort than 99.9% of the population without power? The low-U structure is insurance enough provided you can manage pay the power bill on time. ;-)

His proposed heating system was...

"There are a number of European manufacturers making pellet stoves < > 10kw which are diverting the highest % of their heat towards hot water and a smaller % into the room in which they are located (typical ratio of 80:20). Limited radiators, a small area of underfloor and a pellet stove all in might come in at < half (5£k) of the suggestions I've outlined above."

...as a more cost-effective solution than the full radiant floors or radiaters with heat pumps or boilers at ~10£K. My come-back was to go mini-split, which would come in at about 3£K, and would also be able to cool the place (cooling is problem most UK homes don't have to deal with on a regular basis, but would for a house like this.) And it would be almost twice as efficient than the 10£K+ hydronic output heat pump/radiant/radiator solutions, according to the AECB data:

http://aecb.net/PDFs/HeatPumpsArticleJuly2011.pdf.

Sure a mini-split breaks the UK hydronic paradigm, but so what? It's a paradigm that SHOULD be broken given the nature of the house. The low-U house also breaks the UK paradigm by quite a bit, which is why a return to point-source type heating now makes sense. Whereas the tiny fireplace in the corner keeping you from dying of the cold in your wattle & daub or stone house was a pretty crummy way to heat, the output of such a fireplace would be many times the heat load of the house he's talking about. ANY woodstove or pellet boiler in the space would over heat the place if allowed to burn for very long, even the proposed 80:20 storage/direct-heating ~10kw thing he was talking about. But a mini-split wouldn't- it would cycle a bit at min-power most of the time, and automatically modulate up during design-condition loads with very little change in room temp. It's really a pretty good fit, and VERY comfortable heating in a low-U home, and it's 1/3 or at most 1/2 the cost of the more customary solutions more appropriate to the customarily higher heating loads.

MikeSolar: At the current retail-residential electricity rates and PV prices there doesn't need to be any feed-in-tariff inducements for new installations to drive German sales- the offset to the €0.25/kwh residential rate is incentive enough! The lifecycle cost of the PV output is down around €0.13 (including the costs of borrowing), so it's about half what's being charged for power drawn from the grid. Households with long time horizons can easily rationalize the investment to get at least some of their power at half price for 20-40 years. Early adopters who DO qualify for the high feed-in tariffs turned it into a business, but they're being paid by the ratepayers at-large. The current price of German electricity pays for a lot of efficiency and green-power without further subsidy (and this is as-intended by the policy makers.) As the feed-in tariff agreements made with early adopters begin to expire it's likely that the cost of power will begin to fall in line with other nations & grid sources, but IIRC those contracts are more than a couple decades in length. (Just 6 years ago the German FIT was on the order of~ €0.50, and those people will still be getting paid in 2025.)

Hey that's the way it works here in Minnesota.

No "wattle & daub" here, but low-e thermal panes, high density foam and radiant floors and an air-to-air mini-split. From my own experience designing HVAC systems and personal experience living with most new and old technologies it is clear that in a milder climate such as the U.K. even my slightly over code retrofit would not benefit from radiant floor heating. Dana's point of cooling, perhaps more to the point, proper ventilation, is key to any home insulated beyond current standards.

In my youthful days working on the first "super" insulated slab-on-grade and "berm" homes, we had to watch the electrical lighting loads for heat output beyond the heat loads of the house. Ventilation in the form of HRV and later ERVs was the answer. The next evolution not quite satisfactorily addressed by the ERV is reliable and efficient control of indoor humidity for small structures. In warm climates the dehumidifying setting works very well on my mini-split and unlike window shakers works quite well in a tight house with good windows.

All solid fuel options are more work than most first world countries are willing to do, long term, green or no.

What, there's no wattle & daub construction in MN?

I thought mass-wall fanatic hippies would be all over it as a green construction method, right up there with rammed-earth & adobe! :-)

Hey, don't put down rammed earth and adobe. I've done a few here in Ontario and the owners like them a lot. And I am just slightly too young to be a hippie.

If only homeowners would understand how long the big utilities will take to amortize their NUC plants and big hydro. They might then understand why it is OK to write off a PV system over 20 years+ but we are conditioned to have stupid 5 year paybacks so there is little incentive to think otherwise. The FIT payments are a reasonable way to kick start the system and without them, Germany would not be where it is now, STILL AT THE TOP (although not for long, I know)

My contract is for $0.80/kwh for 20 years. I would have done it anyway but it helps. The same has happened here, turning the system into a business which is why the rules are changing to limit the return.



About British passivehaus, I would still have some tubing in floors, not too much and with VERY mild temps just enough so the women don't have to keep their feet on the couch all the time LOL.

What, no wattle & daub in Ontario either? What gives?

If you heat the place using a diminished area of radiant floor to bring the spot-temps up for a little extra cush-factor, how do you propose to cool this house?

One doesn't normally think of houses in the UK as needing active cooling, but houses with U-factors that low aren't typical, and it isn't always cool enough outside to be able to handle the cooling load simply by opening windows.

My bad. In a rough division of hvac into forced air and radiant, I classed radiators as radiant because they radiate. Silly of me when Dana on the defensive has entered the phase of peppering us with nikpicks and smothering us in verbage.

Anyhoo, here are the qualifications he should have made:

Caveat 1: All-electric is a bet that UK energy policy can find an economical balance between cutting carbon emissions and replacing aging generation plants. While I know few particulars, the aging plants must be base load generators for which are there few options -- either that or British politicians gig antinuke activists at moments for just for giggles.


Caveat 2: Ductless is not renewable in the British sense of the term. In the most country-specific of factors, the UK's regulatory goal is carbon reduction while the U.S. regulatory goal is energy conservation. Our energy code is fuel neutral; theirs is not, penalizing all grid based hvac, including heat pumps. There are people there -- and here -- who say nothing grid based can be considered green, that even clean burning natural gas is a carbon store that should be left in the ground. Plenty hold the opposing view, of course, the point being that the call is not Dana's to make.

Caveat 3 (where we came in): Nine of the contractors the OP calls will tell him ductless is a terrible idea that should be dropped forthwith, while the 10th will be equal parts enthusiasm and inexperience. Dana's answer is a link to a heat pump study that is laughably reminiscent of the GM ads of the mid '90s. (We aren't as bad as you think.) OK, heat pump purveyors may have overpromised in the past and installed them in terrible designs, but, hey ..... We aren't as bad as you think.

Take it from someone with considerable experience banging his head against conventional wisdom. No. 1, when you go against the flow, it's on you to be your own expert, and after said course of study, it's on you again to see that it gets done right. No. 2, altogether too often, the conventional wisdom is right.

I happen to agree with Dana so this in the spirit of cooperation: HEY, GREAT BRITAIN; DANA1 THINKS YOU HAVE IT ALL WRONG. There. That should do it. (Except for the mammoth, turgid response, quoting copiously from the document above, until the eyes glaze over and the reader prays fervently for a tax on pixels.)

Ok todd, in order:

1: I have no doubt that the UK grid is going to be more expensive, but have no doubt that it'll stay on, and be cheaper than in Germany (or even parts of New England, for that matter.)

2: The O.P.'s question was "Question is how to provide space heating without an onerous capital investment? " not what's the greenest possible solution or which had the lowest carbon footprint. Those latter issues were your call, not the OPs, not mine. I made a recommendation that would come in at 2£K less onerous than his proposed system.

3: So, you spoke to 9 of 10 contractors on the O.P.s behalf? Big of you! ;-) Mini-splits aren't new to the UK, but they're mostly used for air-conditioning rather than heating. The AECB heat pump thing I linked to shows abyssmal performance for both ASHP and GSHP hydronic systems in the UK, indicating that rather than "not as bad as", GM-ad style, they're actually WORSE than you think, indicating that the system designers need to get schooled on the subject. This is in contrast to every decent scale third-party testing of air-to-air mini-splits that that they're generally pretty good, many even outperforming the manufacturer's spec ratings, but only "about as good as you think" in general, and being systems-in-a-can there is no associated design risk.

Most early PassivHaus certified homes in Europe used resistance electricity as the primary heating source, with a COP of 1. The average COP of hydronic ASHP systems in the UK were in the 2.2 range, which would be an improvement, but US based field measurements of mini-splits in a US marine zone 4 climate (very comparable tobut slightly cooler & damper than UK winter temp & humidity,) show performance in the mid-3s. Lab testing would indicate that oversizing for the design condition load would add at least a 0.5 in average COP, but OK, let's call it a COP of 3 rather than 4 as the backstop- it's still better than the UK industry average for hydronic systems that would cost 3x as much. On such small heat load even the difference between 2.2 and 3 or 3.5 is something of "who cares" difference on operating cost- and cheaper to heat with twice the heat load of a PassivHaus than heating a PassivHaus with a COP-1 toaster-element the way it's often been done. The hot water heating will still exceed the space heating cost if it's a 4 person household.

Regarding conventional wisdom: The "conventional wisdom" on PassivHaus is to heat with resistance elements in the ventilation air and skip air conditioning altogether. To move to a mini-split (as have most cool-weather first-world Asian homes in Japan & Korea) wouldn't be a risky venture, particularly in a very-low-U house. There IS no conventional wisdom for heating superinsulated homes in the UK yet- the numbers are too small, which is why the O.P. was looking for scaled down versions of the tried and true with a bio-mass fuel twist. But at less than 1/3 the typical UK home U-value there's no point to following that model. It's not that the UK model is wrong for conventional housing, only that it's senseless in a near-PassiveHouse. The caveat on a Scottish PassiveHouse site reads:


"• The equipment must be sized appropriately to the heat load of the house. This will be defined by the ‘Verification’ page in the PHPP software. In a 110m2 house with 3.6 occupants, a stove of 3kW output would be sufficient for all space heating and DHW needs. For a small Passive House, most models will be too large, i.e. the output will be too high. Therefore suitable models have to be chosen carefully."

http://www.sphc.co.uk/domestic-hot-water-solar-thermal

But yet there are still examples of that over-designed type of heating system in UK PassiveHouses that need big buffer tanks to use conventional biomass boilers without roasing, even if a cheap mini-split would have handled the load directly: http://www.sphc.co.uk/underhill-data [“Woodfire F12” wood burning stove with back boiler, sealed to room air. 2 post heaters (water based) in air supply ducts distribute the heat.] Adding any combustion appliances (wood fired or not) inside the building also adds to the air-sealing costs if going for true PassiveHouse levels of tightness too. So maybe the UK does have it all wrong, at least on their PassiveHouse designs. http://www.sphc.co.uk/sites/default/files/images/body/diagram1a.jpg (Was Rube Golberg a brit? ;-) I've designed kludges nearly that messy, so I'm one to talk, eh? )

We are getting closer. One man's kludge is another man's commitment to reducing his carbon footprint. The OP's pellet stove is not a "twist" but a pervasive and conscious effort in GB to embrace renewables (aka biomass.) A cross-cultural expert might counsel him to decide which approach he wants to emphasize to avoid overkill: renewable or passive house. The only "right" answer is the one that works for the OP, eh?

From a policy point of view, reducing carbon is best done on a least-cost point of view, but I fully appreciate the lengths to which some individuals will go, even when the capital costs to meet a low-carb spec are beyond all reason in any financial analysis. But the complexity required on some of the PassiveHouse UK designs to be fully integrated with one another doesn't always produce best efficiency OR cost.

The OP's stated interest being "...how to provide space heating without an onerous capital investment?" (probably in reaction to the extremes taken most UK PassiveHouse builders with deeper pockets), I continue to stand by my recommendation, since it's cheap, cheap to operate, flexible, comfortable, and comparatively better matched to the loads.

Since it's likely to be a bigger operating expense, domestic hot water issues are probably worth more attention (and capital investment) than space heating, but that wasn't the question.

You Canadians, sooooo PC, ehheheehee.

I think of capital as invested human sacrifice. Like a "natural" resource, it is not to be wasted. With few exceptions the real cost of everything we want reflects the effort and risk we (mostly others) are willing to make. The balance, is between self-reliance and cooperation. Both admirable traits when rationally applied. The emphasis is well placed on DHW, as we saw peak loads for DHW easily treble hourly design heating loads back the 80's, when the first artificial energy crunch was created by misguided gov't. policy.

I love the Passivehaus, but not blindly.

How can I have my cake and eat it too?

Morgan, we're in good company!

Many have criticized PassivHaus standards on energy use per square meter as being arbitrary and extreme- extreme to the point where the lifecycle cost of the additional insulation required to hit the spec is higher than simply higher site-energy supplied by photovoltaics driving air-source heat pumps at a somewhat higher loads. The line where it crosses over is wide and gray, but in cooler N.American climates PassivHaus is well out of the penumbra on the other side of the line.

Marc Rosenbaum has a pretty succinct take on the subject- have a slice o' low-carb cake!

http://blog.energysmiths.com/2012/03/a-proposal-for-amending-the-passivehouse-standard-for-new-england.html

PassivHaus, thank you.

Quite succinct a adroit. Once again the Great Dana throwing light - and shadow - on a subject only seen "through a glass darkly" by so many.

Kudos.

Posted By Dana1 on 01 Jun 2012 02:18 PM
What, no wattle & daub in Ontario either? What gives?

If you heat the place using a diminished area of radiant floor to bring the spot-temps up for a little extra cush-factor, how do you propose to cool this house?

One doesn't normally think of houses in the UK as needing active cooling, but houses with U-factors that low aren't typical, and it isn't always cool enough outside to be able to handle the cooling load simply by opening windows.

I have a friend in Shropshire who has a certification in wattle and daub so he can do the heritage buildings. He tells me there is a secret ingredient that must be added to the mix to make it authentic.......



Manure. No sh*t, It is true, apparently when the mix was made the horses or cattle added to the mix and it became part of the current official formula (my friend may be sh*ting me but I will take him as his word LOL) 

As I wrote earlier, I agree that multifuel radiant is overkill in a passive house design, although the wood stove boiler and the solar hot water in the schematic you linked surely furnish DHW as well as central heat. You are also right about the cost. My version of multifuel is coming in at about $15k after careful buying and as much DIY as possible (not much.) That bought me a 61kbtu wood stove boiler plumbed to a 200 gallon heat bank (stainless steel inside 4 inches of polyiso); 1600 sf of radiant floor; an electric tankless as backup; 24-tube solar hot water; and a two ton ductless. What you are still missing is why the UK energy code encourages multifuel, and would not penalize my ductless as part of a multifuel system. Let's start with solar.

Mine heats a 65-gallon tank in a conventional DHW system with one extra wrinkle. When I throw a switch in September, a drain back system circulates heat bank water through the second HX coil in the solar tank, limiting the latter to 125 degrees. Granted, my house won't need much heat in the shoulder seasons, and solar hot water won't contribute a great deal in Dec and Jan., but for eight months of the year, the approach uses solar hot water at 100 percent capacity and at temperature differentials that guarantee high efficiency rates. If you are Dana, you're calculating a significantly faster payback on solar hot water. If you are me, you're thinking no fires until mid to late Nov.

On to heat pumps. A heat bank would give a huge efficiency boost to an air to water heat pump as well. The heat pump runs in optimal conditions during the day. The heat bank takes over at night. A heat bank can also take advantage of time of day pricing. For the moment my tankless makes up the difference if the heat bank falls below 110, but it's a simple change to heat the tank instead.

My ductless is forced air and owes its existence to the high humidity levels in the midAltantic, but it could play a role in central heat. With the thermostat set at a stop loss level of 65, say, it could take over on the many overcast winter days when the cloud cover keeps ambient temps well up on its efficiency curve but takes passive and active solar out of the picture. Dana will say the ductless is sufficient by itself and he is right. I call it a choice -- to laze on the couch or fire up the stove and toast those tootsies. Among the many things we don't know is what firewood costs in GB, although we can assume it is competitive. For me, it's free, and my operative question is how warm do I want to be?

PV/heat pump would not be as comfortable. It would not cover as many bases with US energy policy in its usual flux. It would not be as reliable as a parts of my multifuel system that are inert steel. That said, PV imakes more sense in Colo., and probably here as well with typical homeowners. It's not better for me. Hail Brittania.