Hi from Passivhaus selfbuilder

[Roger Lindley]

Hi everyone,

I'm a "mature" retired electronic/electrical design engineer come computer networking consultant come PH self builder.  See following link for existing building details. http://passivhausprojekte.de/#k_4186

Currently designing second PH for construction in Brinkworth, on Woodbridge park golf course. Build commences 2nd August. Also designing next door neighbours from PHPP perspective.

Scandanavian Lodge design ( planning requirement), Isoquick insulated raft foundation, Beco ICF walls (polstyrene lego bricks according to my wife!), attic trussed warm roof. Approx. 240m2 and 550m3 gross including voids which are within thermal and airtight envelope.

Techie bit. Hmm.. The intension was to have very similar to current house as it works well! However no mains gas so all electric. MVHR to be a Paul Novus 300 with Lindab rigid safe ducting, silencers etc. Thermal store to be Akva Nero 750l (current house has Akvaterm std tank of 500l  with top and bottom DHW coils giving up to 35l per min). Change of size result of no mains gas and probable use of Eco7 electric to supplement Solar PV via Immersun PWM switch to two high temp immersions. Space heating via VEAB CCW 125-6-2.5 in living area duct branch only - no active heating to bedrooms. Summer active cooling via VEAB CWK 125-6-2.5 in bedroom ducting only or VEAB CWK 160-6-2.5 for all areas... 3kW ASHP air to water supplying the VEAB CWK. Secondary DHW loop to provide "instant" hot water to all areas with little potted water wastage (as per current house).

Well that was the plan until I discovered Sunamp and Zehnder Comfocool Q600! So undecided now although no apparent pricing/availability of Sunamp Stack.... Sunamp PV 5kW units look good but only a fraction of the capacity of a 750l TS. Multiple units look very expensive by comparison.

However, need to make a decision soon I guess.......

 

 

 

[Tennentslager]

Welcome Rodger 

Sounds like your an old hand 

I'm sure someone will be along soon to talk about sunamp and all those other mysterious technologies (well to me anyway)

[ToughButterCup]

Recht schoen Gruesse Roger! Passivhaus aus Deutschland wa? Na mach denn! 

You're most welcome. 

Decisions; sometimes stressful, sometimes delicious agony, almost always high-stakes because we have to live with them for the rest of our time in the house. Ask away, learn with us. And if you're anything like me get it wrong a few times and then get it right.

Ian

[Nickfromwales]

Bonjour, from sunny Wales. 

Ask 3 times....

Measure Twice.....

Cut once . 

[tonyshouse]

Might be too late but I would design out active cooling you should need it. Thermal model will inform this and likely suggest external shading 

try to include some mass, concrete floors inside thermal envelope

HW best with immersion as emergency back-up go for a small heat pump for normal hot water 

prop or brace walls during construction.

concentrate on air tightness, where is your air tightness barrier, will ring beams and lintels cause thermal bridging?

solar thermal has to be an option. 

Hope it goes well, 

[Gone West]

Hi Roger and welcome to the forum. It looks an interesting project. So does the polystyrene upstand on the Isoquick slab align with the polystyrene on the ICF walls limiting thermal bridging? How does the trussed roof join the walls to create the same effect?

[VIPMan]

Sunamp PVs are probably most appropriate where you have space constraints then you can take advantage of their energy density ( -  using gross volumes about 3 to 4 times better than a hot water system) With the size of thermal store you propose, 750litres - this will  lose a lot less energy per litre than a small 200 - 300litre system (surface area/volume effect). As long as the total heat generated can be accomodated into your design without causing overheating issues  then the other main benefit of the Sunamp PVs - their very loss standing losses will not be than important to you. We only use our two  Sumanp PV units for hot water and use a cheap 1.2 kW electric post heater in the MVHR supply for space heating. Our twin system  gives the rough equivalent of a conventional 300litre system. We don't have gas by choice and use surplus solar PV and economy 7 to power the two 3kW elements in the Sunamp PVs.

Edited July 17, 2016 by VIPMan

[Roger Lindley]

Well time (quickly) and build (slowly) have moved on. So an update is in order. MVHR is to be a Zhender Q600 comfoair system with the Q600 comfocool attachment. Ductwork is rigid Lindab and currently installed in Tom's, our next door neighbours. We are both pretty much water tight although 5.8M Internorm doors are yet to be installed along with some other Internorm windows and doors. Second week in November for the remaining doors and windows.

I decided to go with SunAmp 5kW PV with 5kW expansion. That is until I got the schematics and found that they (SunAmp) supplied the two units in a series configuration. So flow seriously compromised by 15mm pipework throughout. I was expecting them to be connected in parallel! So I went back to SunAmp to cancel the order and revert to thermal store. However, I am now awaiting confirmation or otherwise from SunAmp on early deployment of 10kW mini stacks which feature 22mm pipework throughout. I will get to know this week so decision in the balance. If we get offered a ministack solution then Electric based Duct heaters, rather than hydronic Veab Duct heaters will be required. We already have the VEAB units albeit the wrong diameter (too small) ..... another story!

In answer to the question by PeterStarck, yes the outer EPS of the Isoquick lines up with the outer EPS of the Beco walls. The wall to truss joint was always going to be a thermal bridging challenge though not a huge issue. The warm roof comprises of 2 x staggered layers of 100mm thick PIR fastened to 11mm OSB deck (Sarking) across the external edge of the roof trusses then membraned battened and tiled. Between the trusses is an additional 100mm of acoustic/thermal insulation followed by the airtight membrane (Pro Clima Intello Plus). The roof insulation continues under the exposed ends of the trusses ( between truss and Soffit) to meet up with the wall EPS. Internally the truss to wall plate joint is filled with Thermal/acoustic insulation to minimise thermal bridging.

6kW of Solar PV is to be installed; 3kW on each of the East and West facing roofs.

If looks like we will use electrically heated towel rails and an electric duct heater in the groundfloor MVHR supply loop only IF we go with SunAmp. This is because there is no stored hot water in the SunAmp based system.

I have attached the space and DHW system as employed in our other Passivhaus. Clearly, this will be different for the current houses but with same functionality. Depends on whether we revert to thermal stores.

roof wall junction detail v2.pdf

Saddleback Heating and DHW.pdf

[Roger Lindley]

SunAmp update. For those interested in the SunAmp products I can confirm that I am are now definitely going with a SunAmp solution as opposed to reverting to a thermal store. I did not want to revert to a thermal store for several reasons, one significant one is the potential overheating of adjacent spaces in summer, even with the Akvaterm stores.

After several emails and telecons with SunAmp personnel I have confirmed that they will deliver a 10kW PV unit which comprises of 4 x PCM cells and 22mm pipework throughout. This is already a proven solution although not yet on the open market. With this configuration I can realistically expect circa 25 to 30 lpm   flow rate, which is good for 2+ "power" showers simultaneously. An added benefit of the SunAmp solution is the extra space in the plant room where I can now locate the three digital shower valve controllers adjacent to the SunAmp DHW supply. 

MVHR first fix will continue this week as I now have the electric inline duct heater(s). I have opted for 200mm diam 3kW units. My PHPP calcs suggest I only need 2kW but the difference in cost (about £4) meant I have gone for extra capacity. Duct temperature will be thermostatically controlled with a setpoint of between 40 and 50C (adjustable) so the added wattage is not an issue. The 200mm dia. units will be reduced to 160mm dia to fit in the 160mm duct work. The added dia. of the duct heaters should minimise the reducton in flow due to the heating elements. I am awaiting schematics of the SunAmp which I will post once received.

[PeterW]

Thanks for that - are you going for ashp ufh then ..? 

[Roger Lindley]

Hi PeterW, there is no requirement for UFH. Total space heating load for the property is only 2kW which will be supplied with the duct heater and supplemented by circa 300W electric heated towel rails in the three bathrooms.  There could be some merit in using a small ASHP for preheating the DHW prior to the SunAmp (as suggested by tonyshouse ) using excess energy from the Solar PV (6kW array). Its very marginal on ROI currently but, of course, energy costs will only rise over time! A we know ASHP's are not efficient at the higher temps needed for DHW but preheating the water through the SunAmp would considerably extend the SunAmps effective capacity. I have already been looking at air to water ASHP's for around £1000 but also need to factor in costs (and space) of a buffering tank , pump and controls of course. The practical issue of not installing some form of additional DHW heating is that once the 10kW of the SunAmp is depleted then will have to wait for an hour or so before we have more hot water at an adequate flow rate. The 3kW element in the SunAmp is clearly not capable of delivering any more than about 2 lpm from cold!  So an ASHP is definitely a consideration on pracatical terms as opposed purely ROI. 

[gravelld]

Sounds like a really good setup Roger.

 

As a newbie I don't quite understand about the water supply though - is your supply capable of 25 to 30 lpm? I thought it was normally more like half that. Do you have some form of cold storage?

[Roger Lindley]

2 minutes ago, gravelld said:

Sounds like a really good setup Roger.

 

As a newbie I don't quite understand about the water supply though - is your supply capable of 25 to 30 lpm? I thought it was normally more like half that. Do you have some form of cold storage?

Currently no plans for cold water storage. A lot depends on your supply of course! Our last new build I installed 32mm MDPE pipe and insisted on a 22mm water meter. That house had over 6 bar pressure which I regulated down. We could run four showers simultaneously at around 8 lpm. For our current build we have also stipulated 32mm MDPE for the incoming feed. In a new build you will always distribute water both hot and cold around the house in 22mm pipe using 15mm take offs for showers and baths and probably 10mm takeoffs for taps other than baths. If you dont have the possibility of decent flow from your mains then you have to go to cold water storage and a fully pumped system. Previous house I have had I always installed a fully pumped system due to inadequate flow. Its not a big issue with the latest negative head pumps as you can store the cold water anywhere suitable in the house.

 

Cheers

Roger

[gravelld]

Thanks Roger, really helpful.

[Russdl]

Really interested in this.

 

I've been toying with the idea of no UFH and no water storage, just Sunamps, solar PV and E7 for our proposed build, It's really interesting to read here from Roger that it seems like a practical solution.

 

Many thanks for posting.

 

[tonyshouse]

Re roof wall junction, I would carry the insulation straight up vertically on top of the wall 50% between the trusses til it meets the roof insulation.