Heat recovery system in new build - where's the vents?

Shoog

https://www.boards.ie/discussion/comment/121786856#Comment_121786856

When we had ours done we replaced the old double glazed units with triple glazed without trickle vents. It's possible to kill trickle vents by taping but they shouldn't be there if the house is new build with airtightness and a MVHR.

In answer to the original query, simply ask to see the MVHR unit, it should be very obvious.

keno-daytrader

My comment about being horseshite was in relation to the whole BER system and not the 22 panels of PV. I'm a big believer in PV power.

You will find A1/2/3 rated houses with 6inch vents (holes) in the rooms. Loads of nightmare stories on boards with these houses hemmeraging money for winter heating.

listermint

https://www.boards.ie/discussion/comment/121786896#Comment_121786896

PV is superb, PV as a crutch to diddle BER sucks.

Shoog

https://www.boards.ie/discussion/comment/121786896#Comment_121786896

Yes it renders the whole BER system a joke. No A rated house should have any room vents that aren't attached to a MVHR unit.

Calahonda52

https://www.boards.ie/discussion/comment/121786668#Comment_121786668

Because it ignores the thermal performance of the building, regardless of energy source.

Coupled with max pv when minimum energy required, and more crucially, the reverse

Padre_Pio

https://www.boards.ie/discussion/comment/121786935#Comment_121786935

My house has mechanical ventilation. Trickle vents in the windows that can be manually closed, and extractor fans in all the bathrooms, kitchen and utility.

Shoog

https://www.boards.ie/discussion/comment/121787112#Comment_121787112

A properly specified MVHR system should replace all of those and reduce your heat losses to a minimum. It's even said when considering MVHR is forget it if you aren't approaching airtightness as it's a waste of money. Extractor fans in all the wet spaces means you are losing significant secondary heat sources.

Our house has been at a steady 19 degrees for the last week with only a half an hour heating on in the morning to generate hot water - and I had to force it on for that. All ventilation is handled by the MVHR.

Padre_Pio

https://www.boards.ie/discussion/comment/121787212#Comment_121787212

Yep, I had considered retrofitting it, but the cost outweighs the benefit. The heat pump is a steady COP of 4 and the electricity bills for whole house are generally under 130 euro a month.

Mellor

https://www.boards.ie/discussion/comment/121786817#Comment_121786817

Why do you think the system doesn’t account for that well?

The energy “usage” is based on heating to a set temperature. As long as the heating system can provide that (low) energy. The house should never be cold.

A cold house happens where the heating system struggiee to supply enough energy or people can’t afford to run it constantly enough. Both which should only occur with a v.high BER.

listermint

https://www.boards.ie/discussion/comment/121787343#Comment_121787343

BER is a crock of **** for warm and comfortable homes.

It's not my fault the system doesn't cater for that well. You only have to look at the ample threads opened with I just moved into my A2 rated home and it's cold and with high winds it's freezing and noisey.

Etc etc etc.

BER has it's uses, but it's easily manipulated.

Padre_Pio

https://www.boards.ie/discussion/comment/121787410#Comment_121787410

PV panels increase your BER. They have no impact on how heat is retained.

"Functional" vents can be blocked for air tightness tests, which is a joke.

Mellor

https://www.boards.ie/discussion/comment/121787410#Comment_121787410

Nobody said it was your fault. I asked why you think it doesn’t cater to that well. You haven’t really explained that part.

If people are falsifying the numbers. The issue there is false numbers (and I agree that’s an issue). But on a fundamental level the concept of energy use is sound.

A lot of complaints I see, are often based in a misunderstanding of how it works. Eg solar panels being a perfect example.

A2 with 22 PV panels, and A2 with Uber-insulation are different systems. Assume they both required the same heating is misunderstanding the meaning.

They should of course required the same total energy to be purchased.

Padre_Pio

https://www.boards.ie/discussion/comment/121787660#Comment_121787660

Sure, but from the SEAI website "A-rated homes are the most energy-efficient and comfortable."

Now, one A rated home may be more comfortable than another. A drafty house is not comfortable, but it's possible to get an A-rated drafty house.

If BER is simply a target, then builders will achieve it in the easiest, more cost efficient way.

As I said before, functional vents can be sealed, so houses with multiple vents will get incorrectly high ratings. The intent is that houses should be comparable, but that is not the case.

Mellor

https://www.boards.ie/discussion/comment/121786999#Comment_121786999

How is it ignoring the thermal performance? The rating is based the total energy performance of the building. That includes the thermal performance.

Take a hypothetical building that requires 100MWh annually (choosing a round number).

Say upgrading the heating system, airtightness, and insulation reduces that need to 50MWh.

Alternatively adding a huge PV array to the roof generates 50MWh annually, would reduce the need for additional energy to 50MWh.

Those building are very different thermally. But the net energy is the same. Energy rating is not a thermal/heating rating.

Padre_Pio

https://www.boards.ie/discussion/comment/121787755#Comment_121787755

Very true, but the house with the PV panel will likely experience larger temperature swings and a heat pump that is running less efficiently. I don't think COP is factored into BER calculations, so it makes it difficult to compare like for like.

Mellor

https://www.boards.ie/discussion/comment/121787733#Comment_121787733

Energy Efficiency is quantifiable, A rated (by definition), is the most efficient.

Comfort is subjective. It’s highly likely that A rated will be most comfortable on average. But they should stress the generalisation part, as otherwise it contributes to the misunderstanding.

https://www.boards.ie/discussion/comment/121787783#Comment_121787783

Definitely. The worse performing thermally will be all over the place.

Swings come down to the sensitivity of the system. How accurately it can measure the temperature, and adjust the heating.

With perfect tracking, there would be no swings. Manually turning it on and off, would be the most swingy. The total energy might be the same. Which also Illustrates that BER is ultimately a measure of energy, not comfort.

listermint

https://www.boards.ie/discussion/comment/121787923#Comment_121787923

Well then it's advertising itself wrong as is the enforcers of it the SEAI.

It is a crock. You know why it's been pointed out, it's easily manipulated. You're moving the goalposts to say it's only about energy use. Then the SEAI need to advertise it as such only.

MicktheMan

The BER system is like an elasticated measuring tape..... useless.

Shoog

The real issue underlying this is that building regs are not prescriptive with regard to what type of ventilation should be used. It should now be a requirement to include active heat recovery ventilation in any home claiming to be A rated. The fact that airtightness can be tested with vents blocked is the real crime here.

Calahonda52

https://www.boards.ie/discussion/comment/121788557#Comment_121788557

The A/T test is designed to find uncontrolled ventilation so leaving vents open will prevent the house from pressurising.

Mellor

https://www.boards.ie/discussion/comment/121787975#Comment_121787975

How is pointing out it rates the energy moving the goalposts? It’s literal stands for Building Energy Rating. It’s a measurement in KWh/m2. You’re reinforcing my point about people misunderstanding it.

It absolutely has it flaws. But saying reducing energy needs via PV is manipulating the system is forgetting what the point is. It’s purpose is solely about conservation of energy.

from SEAI;

A Building Energy Rating (BER) certificate rates your home's energy performance on a scale between A and G. A-rated homes are the most energy efficient while G-rated are the least energy efficient

listermint

https://www.boards.ie/discussion/comment/121790466#Comment_121790466

From their own website blurb.

There's nothing comfortable about an A rated home packed to the gills with solar, a heat pump and big holes in the wall.

Yes it can be manipulated to push really **** houses up the scale relatively easily all the while providing their inhabitants with a not comfortable living.

Mellor

https://www.boards.ie/discussion/comment/121790492#Comment_121790492

The quote I provided is also from the website. The quote you provided, is generally true. Taking a single line out of context is a pretty poor way to try to understand something. If somebody entire understanding of BER is comes from solely on that line, they really don't understand it.

The full paragraph;

The rating scale

The Building Energy Rating (BER) allows prospective buyers or tenants to objectively compare the energy performance of different dwellings on a like-for-like basis. It helps you to understand the energy efficiency of a home and can be used as an indicator of the running costs and carbon emissions associated with heating the home to a comfortable level.

The rating scale looks similar to the energy rating labels for household appliances. It rates the home on a scale from A-G.

A-rated homes are the most energy-efficient and comfortable. They tend to have the lowest energy bills.

G-rated homes are the least energy-efficient. They typically require a lot of energy to heat the home and have the highest energy bills.

It's not a technical summary. It's obviously dumbed down for laypeople. None the less, I've no idea how anyone could read that and not grasp that it is clearly an energy rating. Comfort level is the like-for-like benchmark. Low rated, under provisioned houses, will likely fail be meet that level. It's pretty simple.

A house built to the minimum levels in 2024, is already far better thermally that the majority of houses in the country.

There's nothing comfortable about an A rated home packed to the gills with solar, a heat pump and big holes in the wall.

If the house is pissing out so much heat that it can't be heated, then its not going to get to A rated. We're not talking about an E rated house to an A label.

If there's no point in an a house that needs heating, then there equally no point is a well insulated house that's relying on fossil fuels or main electricity (also fossil fuels). The optimal is a balance of both.

keno-daytrader

https://www.boards.ie/discussion/comment/121791040#Comment_121791040

I'm not sure your seeing the reality the BER system. You're saying it based on the energy performance of the dwelling.

Simply go into the BER thread, look at the many posts of A rated homes absolutely eating energy in the winter time. Also have a look in this renewables thread about heat pump electricity usage of some A rated homes, some of the energy consumption figures are shocking in A rated homes.

I've had 2 BER s done on our new build and never was asked for my blower test results (airtightness). I'm close to a passive result and yet a house that scores a 4.9 ACH will be no different than mine when it comes to the energy efficiency of the 2 houses on the BER.

The BER system is unfit for purpose.

listermint

https://www.boards.ie/discussion/comment/121791206#Comment_121791206

Bingo.

Calahonda52

from above

compare the energy performance of different dwellings on a like-for-like basis. 

What PV does is change the energy source, does SFA for changing the thermal performance of the building.

Re the HP issues

Am doing two pretty identical existing houses, built in 2023, same Buildings Regs

One has a 11kW HP

The other an 8

The DEAP SCOP's are 450% and 208%

Was concerned I was making an error so had it checked with SEAI, consensus is that 8 is undersized

graememk

https://www.boards.ie/discussion/comment/121791428#Comment_121791428

Any idea of the actual scop of the 8kW was?

Was it actually undersized or did it meet the heat loss of the house.

Scop has nothing to do with the heat loss. It's all about flow temperatures and the emitters.

It's how efficient the heat pump can run. And if it's setup correctly it should hit the 450%?

What sort of effect did it have on the BER? Nearly double the [heating] energy requirement?

Mellor

https://www.boards.ie/discussion/comment/121791206#Comment_121791206

I’m not saying it’s an assessment of the energy performance of a building, that’s what it is. It’s literally the entire purpose of the BER. The BER rating (A-G) is based on energy required per square metre, and nothing else.

It’s an estimated based on design specs rather then actual energy use (for obvious reasons). If people are inputting BS specs, or the install is shoddy. Then the result is BS. That can happen, but the issue is the BS data, not the metric of energy per square metre. I'd consider ACH figures that don't make the actual air loss to be BS.

Simply go into the BER thread, look at the many posts of A rated homes absolutely eating energy in the winter time. Also have a look in this renewables thread about heat pump electricity usage of some A rated homes, some of the energy consumption figures are shocking in A rated homes.

I've seen some posts. There was one where an A2 house was cold coming into winter unless the heating was on (it had gas and solar panels). I didn't see the cert, but I assume it's based on heating running, and its offset by the solar. As I said, people misunderstand the energy usage figure often.

There can be issues with the performance data with some HPs. If the specs are BS, the result is BS as I said. But even with accurate specs, heat pumps do use a lot of electricity. Replacing oil with a heat pump will instantly improve BER. The electrical energy use will of course jump. When people say the energy consumption figures are shocking, do you have an example of the figures?

I've had 2 BER s done on our new build and never was asked for my blower test results (airtightness). I'm close to a passive result and yet a house that scores a 4.9 ACH will be no different than mine when it comes to the energy efficiency of the 2 houses on the BER.

I'm not sure I follow what you're saying there. A BER result should consider the airtightness. If they are as low as you say, the BER result should reflect that. What do you mean 4.9ACH would be no different?

https://www.boards.ie/discussion/comment/121791220#Comment_121791220

Bingo? Really. I'm sure I see the parallel with your posts. How would that apply to your complaint about solar? I genuinely don't understand the issue with a PV cell reducing the additional energy a house needs?