A-Rated = Passive??

whatanidiot · 15-01-2013 05:13PM #1

Hey Guys,
I know this is probably a really stupid question but if a house is retrofitted to an A-Rated BER Rating is this then considered a "Passive House"? Or must a house be constructed from scratch in Passive standard to be considered Passive? Thanks for any replies

:)

sydthebeat · 15-01-2013 05:43PM

whatanidiot wrote: »

Hey Guys,
I know this is probably a really stupid question but if a house is retrofitted to an A-Rated BER Rating is this then considered a "Passive House"? Or must a house be constructed from scratch in Passive standard to be considered Passive? Thanks for any replies :)

no.

You can have a 'passive certified house' and it can be B rated.

While the two relate to 'low energy usage' buildings.... they do not co-relate.

Also, the A band has three factors, A3, A2 and A1

Outkast_IRE · 15-01-2013 05:47PM

whatanidiot wrote: »

Hey Guys,
I know this is probably a really stupid question but if a house is retrofitted to an A-Rated BER Rating is this then considered a "Passive House"? Or must a house be constructed from scratch in Passive standard to be considered Passive? Thanks for any replies :)

They are two different things essentially, if you have an A rated home, you may very well have some elements in your home which are similar or near to the passiv standard , but you do not have a passive house.

This page explains some general requirements you need to meet the passivhaus standard.

http://passiv.de/en/02_informations/02_passive-house-requirements/02_passive-house-requirements.htm

whatanidiot · 15-01-2013 06:19PM

Thanks

I'm trying to get my head around it at the minute as my boyfriends considering fixing up his grandparents' old house. If we were to go ahead and start we'd prefer to get it to the best rated we can so don't want to rush anything as it's in an awful state and deciding to knock it may end up the best option. All these different names of houses like Passive, low-energy, eco-houses is a little confusing for me at the minute but I'll get there.

http://www.constructireland.ie/Articles/Passive-Housing/19th-century-ruin-renovated-with-passive-house-aims.html This gives us hope

Is getting a house to A rated a hard undertaking would you think? Would B rated be a more realistic aim?

sydthebeat · 15-01-2013 06:26PM

whatanidiot wrote: »

Thanks I'm trying to get my head around it at the minute as my boyfriends considering fixing up his grandparents' old house. If we were to go ahead and start we'd prefer to get it to the best rated we can so don't want to rush anything as it's in an awful state and deciding to knock it may end up the best option. All these different names of houses like Passive, low-energy, eco-houses is a little confusing for me at the minute but I'll get there. http://www.constructireland.ie/Articles/Passive-Housing/19th-century-ruin-renovated-with-passive-house-aims.html This gives us hope Is getting a house to A rated a hard undertaking would you think? Would B rated be a more realistic aim?

a good consultant who is versed in construction and energy conservation can give you the best advice on what you can do to get best "bang for buck"....

you may aim at A rating initially, but upon this course you may discover that getting from B1 to A3 is simply uneconomical.

In order of priority you should:
1. Insulate elements of structure
2. Make air tight
3. limit thermal bridging
4. Use high efficiency heat source
5. Have good controls over heating
5

BryanF · 15-01-2013 08:21PM

sydthebeat wrote: »

a good consultant who is versed in construction and energy conservation can give you the best advice on what you can do to get best "bang for buck"....

you may aim at A rating initially, but upon this course you may discover that getting from B1 to A3 is simply uneconomical.

In order of priority you should:
1. Insulate elements of structure
2. Make air tight
3. limit thermal bridging
4. Use high efficiency heat source
5. Have good controls over heating
5

The passive house is more about external fabric than the BER, as the BER tends to lean towards renewables at the A level. Nothing wrong with this but Farbic should be first ie reduce heat loss and maximise free solar gain before adding heat.
What's the budget?

MOTM · 16-01-2013 12:49PM

BryanF wrote: »

The passive house is more about external fabric than the BER, as the BER tends to lean towards renewables at the A level. Nothing wrong with this but Farbic should be first ie reduce heat loss and maximise free solar gain before adding heat.
What's the budget?

Not necessarily true. An A3 BER is well achievable without having any renewables on space heating. A condensing boiler with zoned controls, good insulation (at or better than TGD L 2011 table 1) coupled with very good air tightness and thermal bridging. Have more south facing glazing if possible. This will also help the BER.

Be careful of water heating though, the DHW demand isn't dependent on fabric improvements, so you'll likely need solar water heating to meet 50-60% of the annual hot water demand.

whatanidiot · 16-01-2013 01:28PM

At the moment we don't have a budget exactly as we want to see if its even viable before committing to anything, we don't want to start and then realize its going to cost too much. We have a starting budget of €20,000-30,000 for external insulation and to insulate the attic. A new heating system was put in a few years ago but it was really a waste as the house has no insulation. Insects will literally crawl up from the floor boards, fireplace and behind skirting boards so that's not a good sign. It's such an old house is it possible the foundations will need to be relaid? We want to knock an interior wall that was put in to separate the kitchen and sitting room to make a large kitchen/dining room and add an extension to the ground floor for a bathroom and utility as at the moment its only a huge living room, tiny kitchen and normal size sitting room downstairs. We hadn't really expected the house to be in such a bad state as it's been rented out for the last few years (crazy in my mind that people would pay to live there) so we hadn't been in it as his parents dealt with it but now they offered it to us.

gooner99 · 16-01-2013 03:19PM

whatanidiot wrote: »

At the moment we don't have a budget exactly as we want to see if its even viable before committing to anything, we don't want to start and then realize its going to cost too much. We have a starting budget of €20,000-30,000 for external insulation and to insulate the attic. A new heating system was put in a few years ago but it was really a waste as the house has no insulation. Insects will literally crawl up from the floor boards, fireplace and behind skirting boards so that's not a good sign. It's such an old house is it possible the foundations will need to be relaid? We want to knock an interior wall that was put in to separate the kitchen and sitting room to make a large kitchen/dining room and add an extension to the ground floor for a bathroom and utility as at the moment its only a huge living room, tiny kitchen and normal size sitting room downstairs. We hadn't really expected the house to be in such a bad state as it's been rented out for the last few years (crazy in my mind that people would pay to live there) so we hadn't been in it as his parents dealt with it but now they offered it to us.

We were in the same situation a few years back when my Aunt left us her house. This house (which we're still in) is possibly in better condition (1970 bungalow).Some said renovate,some said knock it.In the end when we trashed it out,taking into account that the house had poor insulation,no central heating and is quite small in size (2 small bedrooms,living room,small kitchen and shower room) we decided that once the roof would be taken off, windows out, floors dug up we would be left with only walls.So we came to the conclusion that we would only save a few thousand (if even that) and it even would curtail what we could do in terms of extension and bringing the existing building up to spec.We decided to demolish and replace. We got planning for a 240sqm house, then the recession hit. We are currently going through change of house and downsizing to a 140sqm house. Actually the 140sqm has everything that the 240sqm house had, bar a second living room and sun room. I'd advise getting the current house looked at to see which is the best option,as it can look like a good idea to renovate, but depends on the size of the existing house and the size of extension needed and also what work is needed not only to bring the existing house up to scratch but more importantly up to the latest regs, which costs more now as the regs are getting stricter.

BryanF · 16-01-2013 10:57PM

I'm not sure how you linked my post with

MOTM wrote: »

An A3 BER is well achievable without having any renewables on space heating.

A condensing boiler with zoned controls, good insulation (at or better than TGD L 2011 table 1) coupled with very good air tightness and thermal bridging. Have more south facing glazing if possible. This will also help the BER.

Be careful of water heating though, the DHW demand isn't dependent on fabric improvements, so you'll likely need solar water heating to meet 50-60% of the annual hot water demand.

Anywho, I'd be very interested in more info on this house that complies with 2011 regs. Particularly what size the solar system is?

MOTM · 17-01-2013 10:34AM

BryanF wrote: »

I'm not sure how you linked my post with
Anywho, I'd be very interested in more info on this house that complies with 2011 regs. Particularly what size the solar system is?

You mentioned earlier that "BER tends to lean towards renewables at the A level". - that isn't correct. The A rating can be achieved without doing anything on renewables for space heating.

Also, on the house in the OP, it is an existing dwelling, so TGD L compliance (e.g. for renewables contribution) as demonstrated in DEAP isn't required.
The solar system would however be a good way of reducing the water heating demand, regardless of what is done on fabric.

BryanF · 17-01-2013 06:47PM

MOTM wrote: »

You mentioned earlier that "BER tends to lean towards renewables at the A level". - that isn't correct. The A rating can be achieved without doing anything on renewables for space heating.

Also, on the house in the OP, it is an existing dwelling, so TGD L compliance (e.g. for renewables contribution) as demonstrated in DEAP isn't required.
The solar system would however be a good way of reducing the water heating demand, regardless of what is done on fabric.

Do solar panels not come under the umbrella of renewables? And I'd didn't make a distinction between space & water heating, did I?
The question was is 'A-rated = to passive'

MOTM · 18-01-2013 10:18AM

BryanF wrote: »

Do solar panels not come under the umbrella of renewables? And I'd didn't make a distinction between space & water heating, did I?
The question was is 'A-rated = to passive'

Yes pont taken. Solar water heating is renewable.

...and on hindsight, it would be possible to achieve the A rating or passive house standard (I think) without any renewables. The water heating demand would take a fair share (increasing for smaller dwellings) of the total primary energy but you'd still be below 75kWh/m2 in DEAP. The U values, air tightness and thermal bridging needed would likely be in or around those in TGD L 2011 Appendix E.

fclauson · 19-01-2013 11:44AM

I am no expert (but I do own the only A1 Passive Certfied house in Ireland

)

BER and Passive do conflict - you can have a passive certified house which fails the defacto DEAP Part L test

But they are both based on the same underlying calcs - its only in the final portral and interpritation of data that the differences show up

If you use the DEAP Excel version you can split out the energy consumption figures from the renewables

Focus on energy leakage first (i.e. fabric first) and then worry about energy consumption second

BryanF · 19-01-2013 02:28PM

MOTM wrote: »

...and on hindsight, it would be possible to achieve the A rating or passive house standard (I think) without any renewables. The water heating demand would take a fair share (increasing for smaller dwellings) of the total primary energy but you'd still be below 75kWh/m2 in DEAP. The U values, air tightness and thermal bridging needed would likely be in or around those in TGD L 2011 Appendix E.

??? I give up

MOTM · 20-01-2013 09:26AM

fclauson wrote: »

I am no expert (but I do own the only A1 Passive Certfied house in Ireland )

BER and Passive do conflict - you can have a passive certified house which fails the defacto DEAP Part L test

But they are both based on the same underlying calcs - its only in the final portral and interpritation of data that the differences show up

If you use the DEAP Excel version you can split out the energy consumption figures from the renewables

Focus on energy leakage first (i.e. fabric first) and then worry about energy consumption second

The OP was an existing house for which Part L does not mandate renewables. It asked about getting an A rated BER and passive house. Both can be done without renewables.

If it was a new dwelling, then yes, part L mandates renewables. DEAP does what part L requires of it on renewables.

Renewables are NOT mandated by BER. They are mandated by part L on new dwellings

sydthebeat · 21-01-2013 12:03PM

MOTM wrote: »

...It asked about getting an A rated BER and passive house. Both can be done without renewables.

..

i would argue that getting to passive level in a renovation without renewables is simply nonsensical. You would be at levels of fabric insulation so large that the law of diminishing returns would make it ridiculously uneconomical.

it would also be silly, but thats beside the point.

Getting to A rating with no renewable energy source would also be so uneconomical as to render it ridiculous. The cost of a solar array system or a wood based heating system would be fractional of what it would be to increase the fabric insulation to comparable energy levels.

MOTM · 21-01-2013 12:47PM

sydthebeat wrote: »

Getting to A rating with no renewable energy source would also be so uneconomical as to render it ridiculous. The cost of a solar array system or a wood based heating system would be fractional of what it would be to increase the fabric insulation to comparable energy levels.

The wood based system would lead to a worse BER than a condensing gas/oil boiler. While there are some condensing wood boilers on the market, the responsiveness in DEAP is still slower for a wood boiler than for oil/gas.

Agreed that the solar system installation will make inroads into primary energy consumption. However, does Enerphit (passive house retrofit standard) not push for a very low level of space heating requirement before considering any renewables? That seems to be the case in Irelands first Enerphit house (see news section of RIAI website: 10th January). I'm not sure what the thermal bridging/air tightness on that project was - would be interesting to see what the BER on that project would be with a conventional heating system...

sydthebeat wrote: »

i would argue that getting to passive level in a renovation without renewables is simply nonsensical. You would be at levels of fabric insulation so large that the law of diminishing returns would make it ridiculously uneconomical.

Would the specific space heating demand (15kWh/m2 for new or 25kwh/m2 for retrofit) still not need to be achieved without help from renewables if looking for passive/enerphit certification?

fclauson · 21-01-2013 01:03PM

having done the maths - PV is a better bet that Solar thermal

and gives a bigger kick on your BER rating

A-Rated = Passive??

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