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

Mellor · 19-02-2024 10:54pm

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 · 19-02-2024 10:59pm

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 · 20-02-2024 1:15am

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 · 20-02-2024 7:21am

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 · 20-02-2024 7:49am

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

Bingo.

Calahonda52 · 20-02-2024 10:08am

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 · 20-02-2024 10:44am

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 · 20-02-2024 1:18pm

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?

listermint · 20-02-2024 1:48pm

https://www.boards.ie/discussion/comment/121792167#Comment_121792167

I have a complaint about solar ?

When did it say I have an issue with reducing the cost of energy? I didn't.. don't out words there I didn't say.

I'm getting solar.. I just bought an EV.

My complaint is that BER isn't suitable for what it proposed and in fact it opens itself open to ridicule and mistrust by the general public. It's become it's own box checking exercise. I understand BER inspectors will take a different view it pays the wages.