why passive house?

[G and J]

@nod PS, congrats on moving in!  Hope it goes well.

[Andehh]

14 hours ago, JohnMo said:

What for a year or month?

 

A month! I realise when discuss passive, that's prob an important differential!

 

Direct debit was at £175 but just dropped it to £150, October will be the 12th month for us to see where we end up, but I think £150 should be around the sweet spot, albeit sitting on £160 credit already.

 

What also impacts that is we use dish washer daily, and washing machine daily, tumble dryer couple times a week..... at the very least.

 

We also have octopus cosy for the ASHP.

Edited July 26 by Andehh

[kevinm]

On 25/07/2024 at 11:06, G and J said:

So, imagine in parallel universes that two almost identical builds were happening.  The only difference is that one is going for PH certification and the other isn’t. 
 

All build costs are the same apart from PH consultation stuff and PH certification and whatever else is needed to get a ticket.

 

How much extra do the PH certified project cost?

 

If you build the house to PH spec (use PHPP etc), the main extra cost is the external validation, which I have been quoted £2300.

[Simon R]

7 hours ago, kevinm said:

If you build the house to PH spec (use PHPP etc), the main extra cost is the external validation, which I have been quoted £2300.

My experience from four years ago was that components like windows, MVHR and even ICF blocks carried a significant premium for PH certification.  That may have changed now it's more main stream.

[garrymartin]

4 minutes ago, Simon R said:

My experience from four years ago was that components like windows, MVHR and even ICF blocks carried a significant premium for PH certification.  That may have changed now it's more main stream.

There's a common misconception that components must be certified individually if you want to achieve an overall certification. That's not the case. They just need to meet the minimum requirements for that component class.

 

According to the Passivhaus Institut, while it is strongly recommended to use Passivhaus-certified components due to their guaranteed performance, it is not strictly mandatory for all components to be individually certified. The key requirements focus on the overall performance of the building rather than the certification status of every individual component.

[JohnMo]

31 minutes ago, garrymartin said:

There's a common misconception that components must be certified individually if you want to achieve an overall certification. That's not the case. They just need to meet the minimum requirements for that component class

I read exactly the same when I was researching our build.

[TerryE]

On 24/07/2024 at 23:56, IanR said:

While PH does deliver the low bills that I was after, the greater impact is comfort. I believe it's the lack of temperature gradients across rooms, with no perceivable convection currents, stable internal temps across the day, no perceivable air infiltration, the quietness of 3G glazing and while not specifically PH, the solidity of blown cellulose insulation gives rise to a comfort level I've not felt in any other building.

 

I call our build passive-class or low energy rather than passiveHaus complaint.  For me, IanR hit the spot with his above comment.

 

BTW, we use resistive heating only, and on current Octopus Agile tariff pricing our monthly energy bill varies from about £75 or so in the warm season to maybe £200 for the coldest months.  It's hard to put a precise value for the bill as we take all of the price variation risk on the Agile tariff.  However, looking at the potential monthly savings in going from a CoP of 1 to an ASHP-based 4, say, for the heating element of these costs; These savings are significantly less than amortised cost for the installation, maintenance and depreciation costs of adding an ASHP, so unless something changes radically in our case we won't be installing an ASHP.

 

Edited July 26 by TerryE

[G and J]

7 minutes ago, TerryE said:

 

I call our build passive-class or low energy rather than passiveHaus complaint.  For me, IanR hit the spot with his above comment.

 

BTW, we use resistive heating only, and on current Octopus Agile tariff pricing our monthly energy bill varies from about £75 or so in the warm season to maybe £200 for the coldest months.  It's hard to put a precise value for the bill as we take all of the price variation risk on the Agile tariff.  However, looking at the potential monthly savings in going from a CoP of 1 to an ASHP-based 4, say, for the heating element of these costs; These savings are significantly less than amortised cost for the installation, maintenance and depreciation costs of adding an ASHP, so unless something changes radically in our case we won't be installing an ASHP.

 

Understood.  For us however the whole calculation is skewed by the grant which I’m expecting to substantially pay for our ASHP.  

[JohnMo]

9 hours ago, G and J said:

For us however the whole calculation is skewed by the grant which I’m expecting to substantially pay for our ASHP

Even without the the grant with careful shopping, keeping the ASHP install really simple for best efficiency also, you install unfunded sub £5k for everything. Ours install as it is at the moment (as simple as it can be) would have cost us about £3100 including the UFH. It includes a 6kW ASHP, 210L UVC, 195m² of UFH and manifold a bit of pipe and insulation. Have a thermostat in the house and it switches between heating and cooling.

 

Our neighbour just paid £4k just to replace a gas boiler.

[G and J]

27 minutes ago, JohnMo said:

Even without the the grant with careful shopping, keeping the ASHP install really simple for best efficiency also, you install unfunded sub £5k for everything. Ours install as it is at the moment (as simple as it can be) would have cost us about £3100 including the UFH. It includes a 6kW ASHP, 210L UVC, 195m² of UFH and manifold a bit of pipe and insulation. Have a thermostat in the house and it switches between heating and cooling.

 

Our neighbour just paid £4k just to replace a gas boiler.

So I’ll get over £4K back in used fivers from my MCS installer then.  Cool.

 

On a more serious note are those close to today prices?  And which ASHP is that based on?

[JohnMo]

49 minutes ago, G and J said:

So I’ll get over £4K back in used fivers from my MCS installer then.  Cool.

No they pocket £7500 and charge you another £ lots of thousands, if you are not careful.

 

49 minutes ago, G and J said:

On a more serious note are those close to today prices?  And which ASHP is that based on?

Unvented cylinder was bought last year from City plumbing, it was about £805 plus vat last August. Came with 3 port valve.

 

ASHP, is Maxa i32-V5. Sold normally in UK by Viessmann (around £4500). Billy bargain from eBay, after plenty of research, £1300. Came new in box and original packaging from Italy via a UK company.

 

Need rubber feet, flexible hoses etc as well. Bought all that in 2022, but prices aren't much different, around £200

 

UFH came from outsourced energy shop. (Prices are now cheaper than I paid)

Current prices IVAR 8 port manifold £163.

2 x 300m pert-al-pert £560, plus a few other bits and bobs £100. 

 

You can claimed back, so prices above are plus vat. Except ASHP which came from eBay so vat paid.

Edited July 27 by JohnMo

[kevinm]

On 26/07/2024 at 19:06, Simon R said:

My experience from four years ago was that components like windows, MVHR and even ICF blocks carried a significant premium for PH certification.  That may have changed now it's more main stream.

I am going block and EWI, so cant comment on ICF. Most high-performimg MHRV units have PH certification now, I would be skeptical of any unit making big claims and not getting PH certification.

[Simon R]

52 minutes ago, kevinm said:

I would be skeptical of any unit making big claims and not getting PH certification.

One would have thought so, but it's not universally the case. My MVHR (which I'm very happy with) is the Blauberg SB-550. It does not have PH certification, the SB-350 does. Given the unit efficiencies are the same, I asked Blauberg why the 550 unit was not PH certified. The reason is cost, they sell far more of the 350 units and could not justify the cost of certification on the 550.

True you don't need to have all your components certified to get PH certification, but it's probably a whole raft of pain to use units which are not certified. Our house meets PH requirements and comes in at less that 15kWh per metre per annum. I'm in no rush to get certified, but very grateful for all the work that has been put into PH design.

 

[JohnMo]

We have two Titon units neither are PH certified, there is nowt wrong with them. Could quite easily have chosen a PH certified one from Titon, but it didn't suit out needs flow rate wise.

1 hour ago, kevinm said:

Most high-performimg MHRV units have PH certification now,

I would really doubt that.

[kevinm]

17 hours ago, Simon R said:

One would have thought so, but it's not universally the case. My MVHR (which I'm very happy with) is the Blauberg SB-550. It does not have PH certification, the SB-350 does. Given the unit efficiencies are the same, I asked Blauberg why the 550 unit was not PH certified. The reason is cost, they sell far more of the 350 units and could not justify the cost of certification on the 550.

True you don't need to have all your components certified to get PH certification, but it's probably a whole raft of pain to use units which are not certified. Our house meets PH requirements and comes in at less that 15kWh per metre per annum. I'm in no rush to get certified, but very grateful for all the work that has been put into PH design.

 

 

Heat recovery drops with increased capacity, there is a strong trend to support this, look at the Zehnder/Helios/Brink units. The bigger units in a product family have lower heat recovery efficiency. The SB-350 achieves 79% heat recovery. The bigger SB-550 would be very close to the 75% minimum heat recovery requirement for PH certification. Maybe they dont want to risk the cost if they are not certain that it will pass?

 

17 hours ago, JohnMo said:

We have two Titon units neither are PH certified, there is nowt wrong with them. Could quite easily have chosen a PH certified one from Titon, but it didn't suit out needs flow rate wise.

I would really doubt that.

 

The PH-crtified Titon looks different to all the other HRV3 machines, the filter access is different. That suggests there is more than just the cost of certification at play, looks to me like they made a special unit targeting high efficiency.

 

 

[G and J]

On 26/07/2024 at 11:40, kevinm said:

 

If you build the house to PH spec (use PHPP etc), the main extra cost is the external validation, which I have been quoted £2300.

I wonder how an estate agent would view a PH certified house versus an identical uncertified house.  

[JohnMo]

2 hours ago, kevinm said:

the filter access is different

Same as the HRV10 I have. Basically the front cover comes off. Instead of a patch panel.

[kevinm]

On 30/07/2024 at 12:22, G and J said:

I wonder how an estate agent would view a PH certified house versus an identical uncertified house.  

I would say zero difference. I doubt I will ever get the extra money spent on PH certification back.

[G and J]

34 minutes ago, kevinm said:

I would say zero difference. I doubt I will ever get the extra money spent on PH certification back.

So maybe, being hard nosed about it, I use the PH stuff to improve our design as much as practical within budget and simply enjoy the comfortable result.  

[garrymartin]

17 minutes ago, G and J said:

So maybe, being hard nosed about it, I use the PH stuff to improve our design as much as practical within budget and simply enjoy the comfortable result.

That's exactly how we are approaching it. We want to build to Passivhaus standards, but we won't let that dictate how we want to live and how we want to experience our new home. If there is tension between those things, strict Passivhaus will lose out every time.

[mjc55]

17 minutes ago, garrymartin said:

That's exactly how we are approaching it. We want to build to Passivhaus standards, but we won't let that dictate how we want to live and how we want to experience our new home. If there is tension between those things, strict Passivhaus will lose out every time.

I think that is how we are going to approach it.  Aim for passive standard but don't make it the main goal.

[Sparrowhawk]

On 29/07/2024 at 16:25, JohnMo said:

We have two Titon units neither are PH certified, there is nowt wrong with them.

 

How do you compare their heat recovery to other units, as to me that's the benefit the PH certified MVHR units bring? There's a variation between the SAP and PHI heat exchange efficiency tests (PHI being closer to real world) which makes comparing the numbers between certified and non-certified units tricky - see https://www.heatspaceandlight.com/cheap-mvhr-expensive-heat-exchanger-efficiency/ for a discussion.

 

 

Edited August 1 by Sparrowhawk

[JohnMo]

30 minutes ago, Sparrowhawk said:

 

How do you compare their heat recovery to other units, as to me that's the benefit the PH certified MVHR units bring? There's a variation between the SAP and PHI heat exchange efficiency tests (PHI being closer to real world) which makes comparing the numbers between certified and non-certified units tricky - see https://www.heatspaceandlight.com/cheap-mvhr-expensive-heat-exchanger-efficiency/ for a discussion.

 

 

It seems to have only two distinctions in the article 

1. PH approved 

2. Cheap brands that are poorly insulated.

 

There is a lot of middle ground missing from the article, PH certified isn't the be all, ends all of equipment. The Titon units are neither a cheap brand nor are they poorly insulated. So missing entirely from the comparison made in the article.

 

"How do you compare" you research, you buy cheap brands (you can pay cheap prices), make your choice, then get on with life.

 

Inside a Titan HRV10 - a huge chunk of insulation, within a metal box, very tight fitting filters and heat exchanger. It's a huge unit and the large HE looks small but it's pretty big.

 

 

 

Edited August 1 by JohnMo