Hello, from two Lake District Passive House wannabees

[Bitpipe]

11 hours ago, LakeDistrictEugene said:

 

I'm sure that's true today, but I'm talking about (say) 25 years from now. And I accept it's only a theory. As awareness of the benefits grow, and PH or near-PH becomes more mainstream, then having certification could add value. How about we check back in 2050 and see? ?

 

PS. There was a time when having PV on your roof allegedly reduced the value of your property, but that particular nonsense has been consigned to the dustbin. 

 

I take your point -  you can build a passive house, and enjoy all the benefits, without having it certified but if that's important to you then by all means pay for the certification.

 

I still think perspective buyers will be interested in day to day running costs and comfort vs a confirmed standard they probably have not heard of or may not even be relevant in 20 years.

 

Just be aware that your choice of products for some functions (like MVHR) may be restricted and you will need to pay a consultant as you go - back in 2015 we were quoted around £3k (and the MVHR unit would have probably been more £2k expensive than the one we chose).

[Pete]

27 minutes ago, Bitpipe said:

 

I take your point -  you can build a passive house, and enjoy all the benefits, without having it certified but if that's important to you then by all means pay for the certification.

 

I still think perspective buyers will be interested in day to day running costs and comfort vs a confirmed standard they probably have not heard of or may not even be relevant in 20 years.

 

Just be aware that your choice of products for some functions (like MVHR) may be restricted and you will need to pay a consultant as you go - back in 2015 we were quoted around £3k (and the MVHR unit would have probably been more £2k expensive than the one we chose).

We did not go for cert either. We decided that the cost was not worth it and spent the money on the fabric of the building!!

[Iceverge]

I can see the benefit of certification if you can't supervise the work yourself.  With a diligent and trusted overseer you're likely to be employing someone who knows the importance of thermal bridging an airtightness. A knowledge of which is lacking from the majority of those involved in building. 

[Bitpipe]

35 minutes ago, Iceverge said:

I can see the benefit of certification if you can't supervise the work yourself.  With a diligent and trusted overseer you're likely to be employing someone who knows the importance of thermal bridging an airtightness. A knowledge of which is lacking from the majority of those involved in building. 

 

I would suspect that if you employ someone to oversee the build in that level of detail then you'll be spending closer to 10% of your build budget for project management.

 

Even then most PMs visit site occasionally, maybe once a week at best or at critical moments - I contemplated using a low energy specialist PM at the start of my project but could not justify the fee.

 

Instead I took the approach of using a contractor who was experienced in passive construction and had contractural commitments to airtightness and a build system to guarantee passive standards, and trades who were capable of maintaining the airtight envelope.

 

Getting the necessary U values and minimising overheating is a design exercise, getting airtightness is both good design and on site attention to detail. You then need follow on trades (electricians & plumbers) who won't compromise the airtightness by putting holes through the fabric.

 

 

 

[jack]

1 hour ago, Iceverge said:

I can see the benefit of certification if you can't supervise the work yourself.  With a diligent and trusted overseer you're likely to be employing someone who knows the importance of thermal bridging an airtightness. A knowledge of which is lacking from the majority of those involved in building. 

 

I think it's worth noting that we talk a lot on here about Passivhaus levels of airtightness and insulation, but there's a lot more to the Passivhaus standard than that. Things such as specific controls on cold bridges, modelling of various types of energy use, and other issues like summer overheating are sometimes considered generally by self-builders, but the PHPP software requires strict, quantitative attention to these and many other factors.

 

Certification also ensures that the as-designed house is what is actually built. I think some believe it's just a desk exercise, but you need to show with ample evidence that what was designed and modelled was what was actually built. This adds a time and supervisory overhead, because someone needs to be involved in documenting everything that's required, which itself requires continuous knowledge of what's going on - and coming up - on-site.

 

Personally, I think PH certification is more than just a rubber stamp. Certainly, given two houses with similar airtightness/insulation values, but one with PH certification and the other without, I'd go for the certified on every time. How much more I'd pay is a harder question to answer.

 

[Iceverge]

Out of interest has anyone here had their house certified? 

 

Was it a worthwhile exercise? It would appeal to me as the little I know about it suggests that certified passivhaus performs  as they were designed. 

 

I have spoken to plenty of self builders who have built "passive houses." Double glazing open fires and lots of overheating. I'd be skeptical of anyone who claimed the badge without the proof to back it up. 

 

 

[Dave Jones]

first job is get the services disconnected/moved. If you have gas this can take a while. 

 

forget skips they cost a fortune you want a grab wagon. The chap with the digger who knocks it down will know someone. It makes lilfe easier if you strip as much as you can first, so all woodwork - skirting, doors, wardrobes, kitchens etc and burn. Also all the rads, pipework and scrap it. 

 

You will be charged much less if you can segregate it a little, the digger man will have a grab for pulling out the roof trusses etc so you can burn them.

[LakeDistrictEugene]

On 05/03/2021 at 18:24, Dave Jones said:

first job is get the services disconnected/moved. If you have gas this can take a while. 

 

forget skips they cost a fortune you want a grab wagon. The chap with the digger who knocks it down will know someone. It makes lilfe easier if you strip as much as you can first, so all woodwork - skirting, doors, wardrobes, kitchens etc and burn. Also all the rads, pipework and scrap it. 

 

You will be charged much less if you can segregate it a little, the digger man will have a grab for pulling out the roof trusses etc so you can burn them.

 

Thanks. Good practical advice. 

[Bitpipe]

On 05/03/2021 at 12:42, jack said:

 

I think it's worth noting that we talk a lot on here about Passivhaus levels of airtightness and insulation, but there's a lot more to the Passivhaus standard than that. Things such as specific controls on cold bridges, modelling of various types of energy use, and other issues like summer overheating are sometimes considered generally by self-builders, but the PHPP software requires strict, quantitative attention to these and many other factors.

 

Certification also ensures that the as-designed house is what is actually built. I think some believe it's just a desk exercise, but you need to show with ample evidence that what was designed and modelled was what was actually built. This adds a time and supervisory overhead, because someone needs to be involved in documenting everything that's required, which itself requires continuous knowledge of what's going on - and coming up - on-site.

 

Personally, I think PH certification is more than just a rubber stamp. Certainly, given two houses with similar airtightness/insulation values, but one with PH certification and the other without, I'd go for the certified on every time. How much more I'd pay is a harder question to answer.

 

 

Agree @Jack, we did the PHPP modelling to ensure that the whole performance was within passive standards and to quantify the space heating requirements plus overheating risk - as a result we specified external window blinds on the east and south aspects which massively reduced that risk.

 

We then designed a built a passive standard basement (not that hard, lots of external insulation and inherently airtight concrete), entrusted the above ground fabric build to MBC (who contractually guarantee the airtightness) and used a passive certified window supplier and installer, same for front door. The follow on electric and plumbing  trades were sensitive to the fabric and low energy requirement having worked on MBC before. Aside from that, the rest of the construction was standard. We did not use a passive certified MVHR. As I was the PM, I was effectively the supervisor but given that the majority of the detail was taken care of, it was mostly stopping anyone drilling a hole through a wall etc.

Were we to have used traditional methods of construction and a main contractor, some amount of passive PM would have been required but would have increased the cost significantly. 

 

On 05/03/2021 at 18:14, Iceverge said:

Out of interest has anyone here had their house certified? 

 

Was it a worthwhile exercise? It would appeal to me as the little I know about it suggests that certified passivhaus performs  as they were designed. 

 

I have spoken to plenty of self builders who have built "passive houses." Double glazing open fires and lots of overheating. I'd be skeptical of anyone who claimed the badge without the proof to back it up. 

 

 

 

Our 'proof' is the completion of the fabric to design, the airtightness test, which came in at below the required 0.6 ACH. The low temp heating works as designed and is rarely used, energy bills are low (£1.15 electric (after FIT) and £1.20 gas daily for a close to 400m2 house). Occasional overheating from evening summer sun in the west but we did not build the bris soleil as specified. SAP is A rated.

 

What you have described above is clearly not a credible passive build.

 

 

 

[pdf27]

1 hour ago, Bitpipe said:

Our 'proof' is the completion of the fabric to design, the airtightness test, which came in at below the required 0.6 ACH. The low temp heating works as designed and is rarely used, energy bills are low (£1.15 electric (after FIT) and £1.20 gas daily for a close to 400m2 house). Occasional overheating from evening summer sun in the west but we did not build the bris soleil as specified. SAP is A rated.

 

What you have described above is clearly not a credible passive build.

Certification of any sort is a quality control process, i.e. a prescriptive means of meeting a particular standard.

1. If you're a fully engaged, hands on self-builder who actually knows what they're doing, the value added is pretty limited - you've already driven the quality into the process and know it without someone else to tell you, and are free to chose your own trade-off between capital cost and energy consumption (15 kWh/m²/year isn't a hard number after all).
2. If you're hands-off and relying on someone to do the work for you, it provides you with a valuable means by which you can ensure that your builder does what you are paying them to - although there are other ways and it may not be the most cost-effective.
3. For volume housebuilders, some sort of audited external standard is probably the only way they're going to improve what they do - without it they'll end up continually salami-slicing the spec to save costs.

Given our circumstances I think we're in group (2) and are quite likely to go for certification - we need some sort of external quality assurance, and PH is pretty close to what we want and is a relatively common standard is likely to be more cost-effective than some others.

[Triassic]

On 05/03/2021 at 18:24, Dave Jones said:

first job is get the services disconnected/moved. If you have gas this can take a while. 

 

forget skips they cost a fortune you want a grab wagon. The chap with the digger who knocks it down will know someone. It makes lilfe easier if you strip as much as you can first, so all woodwork - skirting, doors, wardrobes, kitchens etc and burn. Also all the rads, pipework and scrap it. 

 

You will be charged much less if you can segregate it a little, the digger man will have a grab for pulling out the roof trusses etc so you can burn them.

Keep the scrap metal separate. I weighed mine in at Morcambe metals and got over £2,000 in total.

[Triassic]

On 02/03/2021 at 12:45, Bitpipe said:

We had a similar era building and could not even give away the 1500 unused and stored bricks from its original construction (original owner had kept them for a future project)

We used the second hand bricks to create feature walls and an ingle nook fire place.

 

We’ll probably use what’s left for garden walls.

 

Edited March 9, 2021 by Triassic

[Iceverge]

5 hours ago, Bitpipe said:

'proof' is the completion of the fabric to design, the airtightness test, which came in at below the required 0.6 ACH. The low temp heating works as designed and is rarely used, energy bills are low (£1.15 electric (after FIT) and £1.20 gas daily for a close to 400m2 house). Occasional overheating from evening summer sun in the west but we did not build the bris soleil as specified. SAP is A rated

I guess you were in the fortunate position to have the knowledge and time to oversee most of the works of your house?

 

Like you, we choose to accept a little overheating at the design stage with a wait and see approach considering overhangs can be extended later. Also we would likely fail the primary energy ph requirement as we use direct electric heating. I considered these deviations from the standard and was willing to accept them as I understood the consequences and possible remedies if needed. Likewise we had a blowerdoor test. Mainly for my own curiosity and peace of mind. 

 

I'm sure as a diligent self builder your house performs well but if a house in an estate agents window claimed passive house without the certification I wouldn't pay any extra for it. However if it was a certified passivhaus by a reputable certifier I would. 

 

As the ability to personally oversee the details of a build is only afforded to a minority can you see any better independent quality control process? 

[SteamyTea]

6 minutes ago, Iceverge said:

As the ability to personally oversee the details of a build is only afforded to a minority can you see any better independent quality control process?

What would happen if the main contractor/project manager filled to deliver to PH standard. Remedial work would probably prohibitively expensive.

Do you would have overpaid at each stage, but have nothing to show for it.

[Iceverge]

24 minutes ago, SteamyTea said:

What would happen if the main contractor/project manager filled to deliver to PH standard. Remedial work would probably prohibitively expensive.

Do you would have overpaid at each stage, but have nothing to show for it.

It's definitely a risk.

 

At some stage you have one has to accept that it's impossible to oversee the quality of everything and you have to trust the label on the can. Leaving the checking process until the cake is cooked is too late. For instance you could specify an intermediate airtightness check when remedial work is easily achievable. If you tied these various targets to stage payments you should avoid making any unfixable mistakes. 

 

I had 3 areas of concern about our build. 

 

1. Airtightness

2. Thermal bridging 

3. Continuity of insulation. 

 

For instance I did the airtightness myself. Our '"tony tray" got destroyed by the wind and concrete precast floor installers. I was able to remedy this with some sand cement parging and lots of airtight paint. We then airtested (0.3 ach50) before continuing the build. 

 

It the gap between on paper and on site that needs to be closed really I think rather that chasing ever stricter building standards. PH certification is one way to go a step in this direction. 

Edited March 9, 2021 by Iceverge

[Bitpipe]

1 hour ago, Iceverge said:

I guess you were in the fortunate position to have the knowledge and time to oversee most of the works of your house?

 

Knowledge no, time yes. Well, I was living onsite in a caravan and worked from home so was always 'around' but was not hanging on everyones shoulder.

 

Was really a case of explaining the ground rules to new trades, but TBH the spark and plumber already knew the rules and had worked with the frame before.

 

1 hour ago, Iceverge said:

Like you, we choose to accept a little overheating at the design stage with a wait and see approach considering overhangs can be extended later. Also we would likely fail the primary energy ph requirement as we use direct electric heating. I considered these deviations from the standard and was willing to accept them as I understood the consequences and possible remedies if needed. Likewise we had a blowerdoor test. Mainly for my own curiosity and peace of mind. 

 

Yep, only regret really is not putting in ducting to allow for a future split aircon.

 

1 hour ago, Iceverge said:

I'm sure as a diligent self builder your house performs well but if a house in an estate agents window claimed passive house without the certification I wouldn't pay any extra for it. However if it was a certified passivhaus by a reputable certifier I would. 

 

I honestly would never advertise my house as passive (or any kind of 'eco' label, even low energy) nor would many estate agent recommended it. I guarantee you would repel far more buyers that you would ever attract. The number of people who would actually understand what it meant and ask to see certification, I expect you could count on one hand. 

 

if / when I ever come to sell, I hope havinga house in a good location of a contemporary style (that will appeal to some but not all), lots of space and finished to a high standard will be attractive to buyers - the low energy bills and general living comfort will be of interest but that's it.

 

1 hour ago, Iceverge said:

As the ability to personally oversee the details of a build is only afforded to a minority can you see any better independent quality control process? 

 

I think the majority of self builders ensure they can oversee construction to some degree - this does not mean 'over the shoulder' monitoring of trades but a clear expectation of what is required and selecting trades who share that understanding and are competent to execute it.

 

Even the best PM, taking a 10% cut of the build budget, will be on site at most a few times a week.

 

So the key to success lies in selecting contractors and trades who have a proven history in building low energy houses - there's a good reason many here have used turnkey timber frame providers as it de-risks the most critical stage of the construction.