The bout of the decade: Code for Sustainable Homes vs Passivhaus

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The bout of the decade: Code for Sustainable Homes vs Passivhaus - round 1

Posted by Andrew Eagles on Mon, Sep 12, 2011

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In the red corner the Code for Sustainable Homes.

In the blue corner the new Passivhaus standard.

Ding ding…Round one

At Sustainable Homes we provide training on the Passivhaus and the Code for Sustainable Homes. We see a great number of architects, planners, builders and designers on our courses and at conferences.

We have noticed that whereas most developers are rightly proud of completing coded homes, there are still a few who are negative about the code for sustainable homes. On top of that passivhuas is the new kid on the block. Passivhaus this and passivhaus that.

I have always wanted to note down a few thoughts about how the standards work and how they interact.

Passivhaus buildings provide a high level of occupant comfort while using very little energy for heating and cooling. Creating this standard requires:

a maximum space heating and cooling demand of less than 15 kWh/m²/year or a maximum heating and cooling load of 10W/m².
a maximum total primary energy demand of 120 kWh/m²/year.
an air change rate of no more than 0.6 air changes per hour @ 50 Pa.

Code for Sustainable Homes incentivises a high environmental performance across a multitude of different environmental issues. Energy is the most heavily weight section, other sections include, water efficiency, waste, pollution, management on site, health and well being.

Sustainable Homes, the company I work for, has been around 14 years. Lately we’ve noticed a strong interest in the passivhaus standard. This is a positive thing as staff here have always placed a heavy emphasis on the fabric first approach. A potentially damaging addition to these comments is the minority who are bad mouthing the code standard and the misconception of placing a preference of passivhaus over the code for sustainable homes.

Maybe it is in our make up to place one against another but I am not sure the two standards cancel one another out. But people often talk as if they do.

I have a few issues with this:

a) Passivhaus is a brilliant concept. We train people in passivhaus. Building homes without wet systems is a very exciting concept. We should further this. A touch of realism is also needed. Passivhaus is not the immediate panacea.

Many people and businesses in the sector do not know how to design or complete a system which achieves passivhaus standards yet.

It may be that a better process is to build to the concept of passihaus without having the onerous responsibility of getting to a maximum space heating and cooling demand of less than 15 kWh/m2.year. This would mean for instance building with high insulation levels, high airtightness and adequate ventilation.

Here is where I get a little bit frustrated. The Code for Sustainable Homes is doing this. In the latest amendment to the Code for Sustainable Homes, an additional five credits were allocated to the energy category. This deals with how the fabric performs. By significantly incentivising the fabric first approach the code is slowly moving the sector towards a passivhaus type solution.

The Code for Sustainable Homes further encourages a Passivhaus type approach through the fabric efficiency performance requirements at level six. The requirements are to gain a high level of fabric energy efficiency (a heat loss parameter of 0.8W/m2K). This drives many of the central principles of Passivhaus standard (fabric first).

b) It would be as shame to ignore the benefits the other remaining parts of the Code bring us. During my stay at Greenwatt Way, I noticed some real benefits from other elements to the standard. A great urban drain off design,that doubled as a play area. Tremendous sound insulation so I did not hear the nearby airport. A very secure property, so I felt safe and responsible sourcing of materials. That felt good also.

I recognise the Code for Sustainable Homes has the beuarocracy of any quality assurance scheme but maybe this can be streamlined. I am not sure how, without reducing the validity of the checking system but I would welcome your thoughts.

It may also be that 34 subsections are too many. If so, which section do you think should be transferred to Building Regulation now or maybe even left out? What do you think?

So improvements are needed sure and yes new kids on the block are funky and exciting but let’s not forget what old uncle Code is bringing us. Some examples are:

homes with better noise insulation – this means parents get better sleep
assigned recycling spaces – this makes it easier for you to fit your recycling in
homes are going to be more secure when achieving Man 4(short hand for the Management)
builders are likely to be more quieter and considerate while building.
a significant reduction in the amount of unsustainably sourced timber and materials

Go on. For those doubters, uncle Code is annoying, but secretly you like him. Admit it.

Tags: Code for Sustainable Homes, Sustainable Homes, Passivhaus

Comments

Clearly Passivhaus is an energy and comfort standard and cannot be cross-referenced against Code for most of the latter's 'sustainability' criteria. And surely no decent designer would argue against having adequate sound insulation, or space for recycling, or secure premises, and so on. The problem comes where developers trade these criteria off against the core criteria of energy efficiency. Yes ENE1 has minimum requirements but they aren't particularly onerous. And if standard acoustic protection is inadequate, then surely Building Regulations should be strengthened? Secured by Design matters are covered by planning generally, most Employer's Requirments include the need for recycling capacity . . . what makes a Code building any different then a standard spec one? You mention use of eco-materials. One look at the the Green Guide and you would think that any and every common building material is 'green', even A-rated PVC windows! Its clearly a flawed approach. And on water conservation matters, there are many consultants I know who tear their hair out at the anomolies of water management in Code buildings, which, more often than not, increase carbon emissions!

Passivhaus is rigorous and based on absolute metrics, not woolly percentage improvements. It is designed around meeting the very best occupant comfort standards and demands a quarter of the energy use of the proposed 'Zero Carbon' Fabric Energy Efficiency Standard. If you want to insist on Code then fine, but why not also reward those who want to design really low energy buildings by allowing the alternative compliance of meeting Passivhaus instead?

Posted @ Monday, September 12, 2011 9:42 AM by Mark Elton

To agree and follow on from Mark's comments above, the main problem I have with CSH is that performance is aspirational while Passivhaus is measured. Although I have recently qualified as a Passivhaus Consultant, I have also studied CSH and both have their merits. PH does not care where materials have come from and how they were made, just as long as they achieve the required performance. CSH is much more lifestyle-aware and concerned with embodied energy in materials but awarding points for bike racks and clothes lines is nonsense if they are not used. PH is a much more sound basis for fabric performance and energy use but costs associated with the PHPP calculations and the stringent performance requirements do put some people off going for certification. I do think there is scope for introducing grades of compliance with PH rather like the AECB or indeed the CSH

Posted @ Monday, September 12, 2011 1:02 PM by Philip Newbold

I recently designed a small Code 5/6 house to ready for site stage, but the costs of getting all the right certifications from specialists for Code on top of Regs, planning and everything else caused my client to lose her nerve and sell early instead of building it in current uncertain economy. That's the main problem with the Code, a one-off small site costs as much as a 20+ unit development.
Apart from that I can't see any reason not to go for both if you really want to commit to low carbon, then you'd cover all the bases - they don't contradict each other. In the end it will always come down to what's affordable and selecting the best combination. Better to save some carbon than give up because the targets are set beyond reach.

Posted @ Thursday, September 15, 2011 9:11 AM by Frances Hunt

Passiv Haus is a straight forward now global standard where this code issue is difficult to understand and involves all kinds of technologies that in the end have nothing to do with the energy performance of a construction per se.

As you point out the Code for Sustainable Homes includes other sections such as “… water efficiency, waste, pollution, management on site, health and well being”. A Passiv Haus forced by its Standard offers a healthy and comfortable environment anyway, and “waste management”, “water efficiency”, “pollution” and “management on site” should be taken for granted and not distract from facts like maximum energy consumption figures and an high air tightness level.

To me it seems the British idea of energy efficiency, this code business, is to hide the fact that Britain came last in realising what the future’s necessities are in reference to energy consumption; in return now trying to catch up but at the same time trying to avoid hardships for a ceasing trade the British standard must be made overly complicated in order to keep the customer stupid and confused and oneself in business.

Customers do learn, obviously faster than the trade is falling short.

caw

Posted @ Friday, September 16, 2011 12:00 AM by Christian A. Wittke

Great to have a bit of a discussion on this. Thank you both for your comments. I see there have been a few twitter references to the article also. One stating that they thought the Code had ended. Looking at the figures CLG released over 70,000 homes have had design stage assessments. This is a significant number that is likely to grow. More comments can be seen

here

By Andrew Eagles

Posted @ Monday, September 19, 2011 6:54 AM by Allan Guy

I do not know much about this but if i design a box with a door, made the door as leak proof as possible, would this then be classed as Passivhaus std?
Check out this link http://www.jetsongreen.com/2011/09/just-right-airtight-lstiburek-insights.html and this one http://www.buildingscience.com/documents/insights/bsi-053-just-right-and-airtight/view to see what i mean.

I'm with the engineer on this as i too am an engineer and believe in hard proven facts and not a finger in the air number, as plucked by the Passivhaus brigade.

Posted @ Tuesday, September 20, 2011 2:42 AM by Matt

Good grief, everyone!
We seem to be rapidly rowing back from sustainable design here at a rate of knots. The debate cannot, and must not, be about Passivhaus v Code. They do two completely different things. PASSIVHAUS DOES NOT ASSURE SUSTAINABLE DESIGN -IT ASSURES LOW ENERGY AND COMFORT. It is great for low energy (I have my argument about the strict need for MVHR in UK but that is not for here) and 'demand reduction first' is the way to go. However, if anyone thinks that compliance with Passivhaus should be an alternative/equivalent to passing the Code for Sustainable Homes, they are equating 'energy' with 'ecology' and 'sustainable' which is just not rationale and far too simplistic. We need a broad code like CSH, but it needs to be reformed. I would welcome metrics and more compulsion in CSH to align with some of the Passivhaus aspirations, but please do not forget the need for ecological design and the bigger picture. Energy alone is not enough.

Posted @ Tuesday, September 20, 2011 3:10 AM by Fionn Stevenson

Some inteligent comments here - it should not be set up as a fight between the two, but a commitment to seek the wisest outcomes. Another key difference is that Passivhaus is a reliable methodlogy that is based in a deep understanding of energy and buildings - whilst the Code is a tick box approach that doesn't really build a deep undertanding of buildings and sustainability, just a superficial one. Passivhaus as an energy and comfort standard has wisdom and many years of proven experience behind it; the design of the Code has been as much based on 'industry needs' and vested interests as much as achieving good sustainability outcomes. After a handful of years it is already being redesigned, in the same way as we now have BREEAM 'outstanding' because 'excellent' really isn't good enough. Use passivhaus methodologies (even if not going for the standard) to achieve / exceed a number of required Code outcomes and you will find you gain a deeper understanding of low energy sustainable buildings.

Posted @ Tuesday, September 20, 2011 3:30 AM by Steve Charter

I agree with Fionn. Horses for courses and all that... Passivhaus focuses on energy/comfort while the Code for Sustainable Homes has a far broader remit. To ask which one is 'best' is rather like asking whether jazz is better than cookery. Such debates are meangingless and, dare I say it, unhelpful. Far more useful to lobby to get Passivhaus accepted as an optional, alternative, 'deemed to satisfy' route to 2013 Part L compliance.

Posted @ Tuesday, September 20, 2011 3:41 AM by Neil Cutland, Cutland Consulting Ltd

@Matt

I would be very interested to learn more about the part that is what you say the "finger in the air number"? Or do really not know much about this.
caw

Posted @ Tuesday, September 20, 2011 3:41 AM by Christian A. Wittke

The PassivHaus is an excellent system. It is a standard developed by a group of architects and engineers that produced a low energy formula based on research and a set of design assumptions. This is great as long as you agree with the initial targets, and consider the climate it was designed to operate in. German and Austrian winters are different to UK or Italian ones, and the design decisions made in the best way to avoid carbon emissions are not universally agreed on. Flawed though they are, SAP and CSH give far greater design freedom, and so encourage innovation, not only in energy engineering, but also in affordability and innovative technologies that are needed now an in the future. PassivHaus has also had its moments where the wheels come off, where occupants retrofit heating or where dwellings regularly overheat. It is has been, and will continue to be, a brilliant contribution to change, but let's not take it in an unconsidered way.

Posted @ Tuesday, September 20, 2011 4:44 AM by Matthew Wright

It does seem like an unfair fight given the multitude of other aspects that the code looks at. I think Passivhaus versus SAP would make an interesting battle as they are bothe dealing with the energy demands of the dwelling. My money would be on passivhaus!

Posted @ Tuesday, September 20, 2011 4:52 AM by Pat

I believe there is a perception issue when it comes to marketing a finished product regardless of which standard has been used. The end users are becoming more savvy with jargon. To illustrate, which is easier to market: a "Passivhaus" or a CSH - level 2, 4 0r 6 home? There is a pre-existing perception that a PH has an attached level of quality etc whereas very few people can see a tangible benefit between a CSH2, 4 or 6 home, let alone design & build one. A beneficial code has to have realistic, measurable levels which translate easily into "this will dramatically reduce your energy bill and heres the proof".

I also suspect that until manufacturers can develop better products to meet a higher standard instead of using the regs as a sliding scale against their existing product range, woolly codes or regs will remain unchanged

Posted @ Tuesday, September 20, 2011 6:57 AM by Graeme

I have a simple question; why can't we combine both, in fact all available standards, under one umbrella? This will help to have one very good standard or process. Also, it will be easy to master and develop one standard rather than working on 1000 standards. From the above discussion I understand that PH can fulfil CSH but other way around looks difficult. Thus, CSH should be integrated within the larger framework of PH, and PH should be integrated within the govt. standards, policies, etc. Perhaps, all available standards such as BREEAM, CSH, PH, Part L, other building regulations, etc. all should be under one umbrella with ultimate goal, to delivery safe, healthy, comfortable, green built environment for the current generation and generation to come.

Posted @ Tuesday, September 20, 2011 9:44 AM by Amey

The last comment misunderstands...it is PH which needs to be integrated within larger framework of CSH, not the other way round. Energy and comfort is a subset of sustainable design, not the other way round. PH cannot 'fulfil' CSH, but it can make it more rigorous in relation to energy and comfort. We need more rigorous standards for other aspects of CSH such as waste, materials etc which PH cannot provide.

Posted @ Tuesday, September 20, 2011 10:10 AM by Fionn Stevenson

Fionn is absolutely right of course but the sustainability standards within Code/BREEAM need serious review. How about AECB water standards instead of the Code which always seems to lead to rainwater harvesting at the dwelling level? We need a better, independent way to compare embodied energy and environmental impact (coming soon with the EU standard maybe?) and I still maintain that if Building Regs sound insulation standards are not good enough then they should be improved vais the AD's. We shouldn't get into a scenario where electrically heated bat boxes are rewarded for biodiversity or electrically chilled water in schools is the norm. (I recommend Architype's excellent 'BREEAM trailer' cartoon, available via Jon Hines' 1st Anniversary presentation on the Passivhaus Trust website). I also think the opportunity for designing out construction waste is completely missed in Code/BREEAM. So lets have a propoer national debate on the subject and aim for a sustainability standard with sensible targets, the right outcomes and where Passivhaus is accommodated and rewarded.

Posted @ Tuesday, September 20, 2011 10:36 AM by Mark Elton

I agree with fionn and neil cutland (and others). The rigor of Passivhaus into the code, the AECB water standards into the code, and a real sorting out and simplifying (eco-value engineering)of the code as a whole. we must reduce costs whilst increasing rigor and effectiveness of outcomes across the sustianbaility spectrum. It may be of course that the code as it is framed wouldnt withstand such a rigorous redesign. But it does need to be redesigned. And we need a broad, effective but flexible code. mmm. meanwhile - yes, to passivhuas as a deemed to satisfy route for the regs. Ideally same for aecb silver....

Posted @ Tuesday, September 20, 2011 10:43 AM by andy simmonds

As one who comes from a much more severe climate than the UK may I be permitted to add a few observations. We have insulated 3 of the dozen or so Passivhauses built in North America in varied climate zones - Louisiana, Colorado and Minnesota over the last decade. The houses are fine and perform well, but as one offs for people who can afford them. With the massive walls and very high cost per square foot I don't see the general public ever taking to them. For meaningful reduction in national CO2 emissions to occur we have to think of how to get thousands of houses to meet more rigourous energy standards. In Canada we developed the R 2000 standard 30 years ago which was concerned with achieving energy efficiency in a cold climate, and very quickly it became obvious that controlling air leakage is extremely critical to ensure performance in the real world. The lessons learned had a great influence on developement of building codes over time. It seems to me whatever side of the debate you are on the objective is still the same, ie. to reduce energy consumption and CO2 emissions. A concern I have in the UK is the over-reliance placed on U value in the Building Regs. U value only measures thermal conductivity through solid materials at one temperature, 20C, and does not provide a measure of wall performance at low or high temperatures or when the wind is blowing. Here in North America the codes have moved from a prescriptive U value (or R value as it is called here) approach to a performance based standard where what counts is the energy actually consumed in the building not the attainment of some arbitrary U value in the wall. There is very good software available that can accurately predict performance, because air leakage is factored in. An evolutionary, more gradual approach, such as the CFSH embodies, may frustrate those who want the most reduction in energy consumption possible right now, but it is more likely to be accepted by big builders and the public if change comes in incremental stages and provides time to adapt. Concern for aspects of sustainability aside from energy usage in the CFSH is certainly desireable too. However on the Passivhaus side the air leakage standard is meaningful and it is probable that the energy consumption measured on the house as built is more likely to be closer to the pre-build calculation. The current air leakage standard in Part L permits the building of houses that are equivalent to living in a tent, which may be ok in winter in the UK, but people would freeze to death in Canada if houses were ever built this loose. Adoption of a tighter air leakage standard approaching Passivhaus in the current Regs would go a long way to attaining the energy performance we all are working for.

Posted @ Tuesday, September 20, 2011 11:49 AM by Jeff Hood

The Salford Low-Energy house preceded the building of the first PH houses in Darmstadt by some 15 years. The Salford houses have had 30 years of occupancy and various POE's have been conducted over the years and over-heating has never been a complaint. Yet recent research conducted at Arhaus Uni indicates that many PH houses overheat causing thermal discomfort and/or requiring mechanical cooling. The research reports that PH houses can use more energy than a traditionally built house due to cooling loads required to provide thermal comfort. Why not combine the CSH with the Salford Low-Energy house?

Posted @ Tuesday, September 20, 2011 2:21 PM by Peter Keig. Eco-Energy (NI) Ltd

So, as there must be a record of 30 years for the Salford LEH then what are the figures, details? Was it below 15kW/m²a? Then I must ask: what took the British market so long and why did it not become the standard 29 years ago??

This discussion is diluting the principles and mixing up the standards! What is the purpose? Do you want to mix in a Standard of the past to create one for today and then the future?

That's rubbish!

PH is clearly defined, CSH is as well but just includes other aspects that - again - should be common sense anyway: like waste and water management. What is so new about that? Look into other countries where waste and water management is 20 years ahead of Britannia!

The UK does not even meter the water! PH overheats? Needs more energy than traditionally built...! Give me a break! Who are you, the guard of a dying species?

caw

Posted @ Tuesday, September 20, 2011 3:14 PM by Chritian A. Wittke

Dear Chritian. The reports on the Salford low-energy house and from Arhus Uni are both peer reviewed and if you google them you will find the details you require. Perhaps you should also take a look at other information from organisations such as MINERGIE , Active House, etc

Posted @ Wednesday, September 21, 2011 1:38 PM by Peter Keig. Eco-Energy (NI) Ltd

Fionn, Could you send your email address again please re the reports.

Posted @ Wednesday, September 21, 2011 1:45 PM by Peter Keig. Eco-Energy (NI) Ltd

Dear Peter,

Thanks, I don’t believe in anything else but my knowledge, experience plus common sense and I am open for any aspect and taking on what makes sense to me: this is not trial and not error free – but experience mounting.

Peer review is a process of self-regulation by a profession or a process of evaluation involving qualified individuals within the relevant industry. Peer review methods are employed to maintain standards, improve performance and provide credibility.

Well, thank you! The keywords are “self-regulation”, “within”, “maintain” and “provide credibility”. And Minergie is no different plus outdated.

It is pure “BS” even before you add it all up.

That is why and what I exactly do not trust. Banks have constantly peer reviewed themselves before they became banksters, the British auto industry did the same and wiped itself out; British construction industry is on the same path. Don’t mention politicians!
If one wants to believe in tradition as the only way forward then good luck.

Of course, I took a look and informed myself before I posted here and said what I have to say. I have no reason to change my above view.

caw

Posted @ Thursday, September 22, 2011 4:55 AM by Christian A. Wittke

I am tempted to say "calm down dears" in a Michael Winner kind of way.

I have spent 40 years watching the volume house builders blighting the UK landscape with their hideous, leaky, little boxes to minimum standards and maximum profit. Until our clueless Government adopts a "fabric first" approach to energy conservation in the built environment and has the guts to ramp up the Building Regulations to PH standards, nothing will happen in the UK apart from a handful of exemplar projects demonstrating how it should be done. As a consequence, the occupiers of these genuine sustainable buildings will be the only ones left smiling when all the oil and gas is gone or when energy prices have gone where we all know they are going.

With respect, discussing the relative merits of the CSH and PH is looking more and more like arranging the deckchairs on the Titanic to me

Posted @ Thursday, September 22, 2011 5:58 AM by Phil Newbold

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