Why study 'passive' housing.

ardara1

Hello Sinner et al

Just to take this discussion in another direction - WHY study for Passive Haus at all?

Whether a dwelling meets this standard or not - it still has to be measured by the national methodology - DEAP in Ireland SAP in UK?

As for thermal bridging, the conventions for measuring under PH is different from the national standards - so do you do both?

UK regulations (Draft) have considered PH standards (Along with 8 other methodologies) and have announced national standards (but not PH) - still measured under SAP.

It will remain the same in Ireland.

Just asking the question. Still an admirer of the movement.

sinnerboy

I have spoken to several clients who have looked past these islands to the PH standard . The PHPP has a track record of delivering in reality what the design intended. Sadly the same cannot be said of national building regulations .

sydthebeat

just a note, ive split this away from teh funded phpp thread as i think its a bit off topic. The original thread was an simply an informative thread seeking interested parties.

I think this thread will be a lot more expressive and engaged.

personally, ill post my views later...

beyondpassive

The national methodologies transposing the EPBD directive are an asset rating system. Its a method of comparing a wide range of building types against a national benchmark. It gives a rough benchmark on how much primary energy is likely to be consumed. A very welcome addition to the sustainable economy agenda which draws attention to energy use in buildings. However there are substantial bias build into the algorithm to take account of existing construction techniques. Heat gains and losses are simplified. In order to roll out a universal methodology to our construction industry for bith new and existing buildings, it would not be warranted to have a rating system which focuses primarily on only the most efficient house types.

Passive on the other hand is more scientific. It is a performance rating tool, so the the projected building's estimated energy use should be close to the actual measured energy use. Independently verifiable calculations using PHPP have matched observable reality with remarkable precision. The passive house institute (PHI) realised early on that mechanical heat recovery ventilation was warranted for energy efficiency.

I find with clients looking at energy efficiency, once we've done the obvious like bumping up insulation between 220-320 in the fabric and minimising all cold bridges, the questing of ventilation comes up. In pure energy terms the mechanical Ventilation heat recovery is just about cost neutral, so the hard sell is the added benefits of air quality and heat distribution. Once their convinced by MHRV and can use it to illiminate rads to bedrooms, you're on the Passive track and DEAP is of no use to you.

PHPP is great to try out different combinations of solutions. It Lets you see the subtle differences if you go for a cheaper window while say, insulating the services cavity to compensate. It is very compehensive and can be mined for very detailed information such as heat load for space and heat load for water with or without a particular solar system. For the TGD Part L DEAP will need to be upgraded to allow this level of interrogation and most importatly focus on energy demand rather that energy production.

sydthebeat

i dont think comparisons to DEAP are warranteed or fair. They are, as BP above has describe, two different animals.

to ardaras point above as to a buildings rating under the two methodologies... well, phpp is not a rating system, its either or.. either it meets the target values and is classified and certifed 'passive' or its not. Look at the two passive houses in carlow... certified passive but B1 rated because the main space heating system fuel is electricity.

regarding renewables in DEAP and building regs, i think we all would agree that it was ill conceived to equate the renewable requirement on a 'per sq m' basis rather than a percentage of energy demand. perhaps the shortfall in DEAPs algorithms were understood and this was not possible. But i definitely think its something that needs to be addressed in any future ammendment to part l.
Personally, if i was handed a passivhaus certification on a dwelling that didnt have a renewable energy source, i would have no problem signing it off.... because i understand the calculations and spirit behind both. I would have no problem arguing the toss in a court of law should that be necessary. Building regs are challanged frequently.

I think its a much more applicable argument to debate the 'bells and whistles' approach of the passivhaus institute in the acceptance of 'bolt-on' technologies to resolve an issue. There is no account made for embodied energy, carriage energy, etc. There is a viable case to be made that a more ecological 'green' build is actually a better direction to take. Local and traditional skills used, local materials, co2 'sink' build types etc.
Using materials with neutral or positive global warming potential (GWP) elements.

passiveacademy

Hi there

Good question on 'why go Passive' when the Irish Building Regulations require application of the DEAP approach. In my experience, the principles of Passive House will always be of benefit to people designing or building a house, even if they really don't care for achieving the standard or getting their house certified as a Passive House. <SNIP> we only design to the Passive House standard and nothing less. We still have to produce a BER for each project, which invlves some duplication of work - nevertheless, we think it is worth the effort.

<SNIP>

Mod Edit: Please read the forum charter before posting again. Do not shill your business here.

passiveacademy

I want to pick up on your comment that the MHRV in Passive Houses is just about cost neutral in pure energy terms. In fact, it performs much better than just being neutral. In the Passive House that I built in Wicklow in 2004, the energy consumed by the MHRV per year is approximately 600kWh. However, the heat recovered by the equipment is approximately 3,000kWh per year, a COP of roughly 5 (as monitored by The Energy Research Group in UCD). And this COP can be improved upon depending on the level of airtightness as well as the efficiency of the equipment.

If you want to 'close the deal' on convincing a Client to use MHRV, I find the best way is to show them a used filter clogged with gunk and get them to imagine that this is what they are normally breathing in their homes. Now that I think of it, I really should keep all the filters that I use and pass them on to people such as yourself so that you can convince your Clients.

<SNIP>

Mod Edit: Do not shill your business here.

ardara1

sinnerboy wrote: »

I have spoken to several clients who have looked past these islands to the PH standard . The PHPP has a track record of delivering in reality what the design intended. Sadly the same cannot be said of national building regulations .

The thinkg is that like SAP oin the UK, DEAP will be revised at the standards are tightened, and like the UK, aminimum standard will be set for heatloss - (39 & 46 in UK).

DEAP will be where the game is at - always, PH lead the field in pushing for half decent buildings - but the national methodologies have caught up (Well UK any way - and our own wizards in the DOE will just copy what they do.)

beyondpassive

ardara1 wrote: »

The thinkg is that like SAP oin the UK, DEAP will be revised at the standards are tightened, and like the UK, aminimum standard will be set for heatloss - (39 & 46 in UK).

DEAP will be where the game is at - always, PH lead the field in pushing for half decent buildings - but the national methodologies have caught up (Well UK any way - and our own wizards in the DOE will just copy what they do.)

Sorry, can you give us those points again Ardara, i'm not sure I understand you.

ardara1

beyondpassive wrote: »

Sorry, can you give us those points again Ardara, i'm not sure I understand you.

SAP has been updated to come into play with the new Part L (Probably October) this came within the consultation documents......

The preferred metric is kWh/m²/yr
covering space heating and space cooling
energy demand (modelled utilising a
notional dwelling assuming natural
ventilation and excluding any internal gains
from the domestic hot water system)

Apartment blocks and mid terrace
houses have a maximum energy demand
of 39 kWh/m²/yrd
Semi detached, end of terrace and
detached houses have a maximuenergy demand of 46 kWh/m²/yr

I have know doubt that Irish TGD L will not read much differently when/if published.

sydthebeat

ardara, i cannot see how the twain can meet.

DEAP / SAP is a rating tool which makes assumptions to "form a notional dwelling" in order to compare like with like.

PHPP is a lot more subject specific and, as has been posted previously, certified buildings tend to perform close to predicted levels.

In my opinion these are two separate methodologies based on fundamentally separate principles.