EPC rating destroyed by Positive Input Ventilation (PIV)?

EPC rating destroyed by Positive Input Ventilation (PIV)?

9:32 AM, 30th August 2023, About A year ago 46

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Hello, I own three fairly typical mid terrace solid-brick houses. All have double glazing, loft insulation and gas central heating. Over the last year I have had Positive Input Ventilation (PIVs) installed in all three.

These have been great in reducing condensation and mould, and the tenants and I are very happy with them.

I had an EPC done at one of the properties today, and it has been rated an E. The assessor says that the PIV ‘batters the EPC’!

How can something that costs very little to run, and has such a positive effect on the living standards and health of the tenant, be viewed so negatively when it comes to an EPC rating?

Thank you,

Paul


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Bryan

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12:16 PM, 30th August 2023, About A year ago

If Mike Ellis is correct then ask the assessor to redo the assessment. Check with Elmhurst who train EPC assessors and provide certification.
However, as Glen said EPC system is not fit for purpose. Recent property I did 100mm insulation all round, but one part could only fit 75mm. Assessors said software only allows 50 or 100, so he would have to downgrade to 50mm. I had to put 25mm insulated plasterboard over that section to get back to 100mm.
Now SAP calcs are the latest and an absolute mess, 3 assessors 3 different results. Is there anybody in Government with any technical knowledge?

Mike Ellis

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DPT

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12:38 PM, 30th August 2023, About A year ago

Ask the manufacturer for their opinion and possibly evidence that you can use to force the Assessor to re-grade.

Beaver

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12:43 PM, 30th August 2023, About A year ago

Can you be a bit more specific about the technology here? So this is a positive input ventilation system and not a heat recovery ventilation system? Is this correct?

Jim K

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13:01 PM, 30th August 2023, About A year ago

Reply to the comment left by Teessider at 30/08/2023 - 10:10
If the 'cause' is Ts consistently leaving windows shut, blocking trickle vents, dryingcolthes on rads etc then I belive it does deal with the cause.
However a really interesting dnippet I will lodge in the memory.

EPC Wiltshire

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13:07 PM, 30th August 2023, About A year ago

Reply to the comment left by Mike Ellis at 30/08/2023 - 11:16Request an aduit of the epc by the accrediting company, the get is reassessed without mechanical ventilation choosen

Beaver

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13:57 PM, 30th August 2023, About A year ago

Reply to the comment left by EPC Wiltshire at 30/08/2023 - 13:07
Do you have any more detail on how you go about having the EPC audited/checked for accuracy?

Rob Crawford

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14:30 PM, 30th August 2023, About A year ago

I asked a very experienced EPC assessor whether a positive air vent system I have recently installed to reduce humidity (and hence mould) and he said it shouldn't make any difference. So I would seek a second opinion, maybe ask the question on the assessor's views before booking him/her!

East Midlands Energy Efficiency

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15:16 PM, 30th August 2023, About A year ago

Okay, let's start with the definition of mechanical ventilation for domestic properties under SAP/RdSAP. For these purposes only, a mechanical ventilation system is one that conditions the air of the whole house by use of permanently running fans. This can lead to confusion to start with as extract fans in wet rooms alone which switch on and off don't count while permanently running extract fans in the same locations could.

As for PIV, it does meet this definition. However, the next stage is to consider how it is best modelled. At this stage more confusion arises. If the PIV system only moves air from a loft space into the house, it is modelled as natural ventilation (as stated above) as the energy efficiency improvement of using warm air is offset by the fan power so effectively it has no effect. But, if the PIV system uses external air from outside the loft space and puts this into the property it should be modelled as mechanical ventilation.

Mechanical ventilation in most properties is a smart rule triggering an automatic audit by the Accreditation Scheme. However, if you are concerned about an EPC you should formally raise this with the assessor in the first instance. If they fail to respond or you are still unsatisfied, you can escalate the complaint to the Accreditation Scheme (Contact details are shown on the EPC). Don't expect this to be a quick process but it does work eventually.

Luna

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15:35 PM, 30th August 2023, About A year ago

I have successfully queried an EPC with the assessor who changed if from a D to a C once I had clarified the insulation in the flat roof. The problem is they quite often "assume" things about the property which is incorrect. In my case, she had assumed there was no insulation in the flat roof.

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