EPC Ratings Getting Worse over Time

[RossThompson87]

Hi,

This is more of a general thread than an IES one... I've been working for a client who already had an EPC done in 2009 and they got a rating an E rating.

They then decided to go for a refurbishment and spent a lot of money on new more efficient lighting. As a follow up they decided to get a new EPC assuming the improvements would get them a better rating and potentially more rent.

I completed a new EPC (in 2013 regs), and the lighting was much better, and the overall energy consumption dropped by around 16%.

However due to all the methodology and fuel factor changes the EPC rating is now "136 F". Despite hours of work this isn't really worth lodging!

Does anyone know a nice way of explaining this to clients? I can see a few problems ahead when EPCs from 2008 need renewing and the ratings come up much worse.

Has this happened to anyone else?

Ross

[Complex Potential]

This is a very real problem.

Managing client expectation from the start is basically your only option here but only the most experienced assessors are likely to see this one coming.

In your situation there's nothing you can do except clearly place the blame at the door of the BRE (I think). The best way to do that would be to run a version of the model under the old NCM and show the client the difference.

I agree that this is going to just keep getting worse....

[Rob]

One thing to bear in mind is that there were no EPC conventions pre 2010, so the original EPC may not have included the same details as the one you've done to the current conventions.

It may be worthwhile downloading the xml file from the epc register to see what inputs were included in the original assessment.

[Complex Potential]

Although the conventions document is part of the picture, the vast majority of the differences can be traced to the NCM methodology changes. Ross isn't really questioning why it is different, he's just venting about it

[Rob]

The NCM changes to methodology and fuel emissions factors apply equally to the reference building and the actual building so this shouldn't have a substantial impact on the ratings. If anything, the updated methodologies provide greater opportunity to account for daylight dimming, constant illuminance control, etc. so enable you to achieve better ratings as these aren't included in the reference building spec.

When i've looked at the NCM updates these have generally changed EPC ratings by a couple of point at most. If Ross is looking at a change of over 11 points then this sounds like more than you'd expect from methodology changes.

Personally, i wouldn't lodge it as MEES come into effect 2018 and that would prevent the building being let if that's what your client wanted to do. Your best bet is to identify how they can get it to an E and discuss it with your client

[Complex Potential]

Sorry Rob but I can only partially agree there. While in general it is often not too noticeable, there are certain building set ups that can be impacted quite significantly.

In theory applying the same changes to actual and reference building should be equivalent right? Well... not necessarily. If you had a particularly poorly performing element that was contributing to an end use that was a small component of the regulated carbon emissions it may not have been a problem. But if the methods change to see that end use base demand increase, suddenly it is a problem.

Also, I'm fairly sure the lighting changes in 2013 have had quite an impact because the actual building now needs to have the design lux level input if it is higher than the notional/reference whereas before it would match in all cases.

[RossThompson87]

Hi,

Yes I was just setting up a generic thread as I can see more and more unhappy clients as we approach 2018 and better ratings are required.

For my specific case, there was quite a big enquiry. We did dig into the XML file from the previous EPC. (The client even got a second independent assessor to verify my model!) It turns out a lot of the energy figures were actually very consistent, it was just the rating that was different.

In fairness we are comparing an SBEM model done under 2006 methodology with a DSM one under 2013 methodology.

Category...............................| 2009 EPC |...... | 2016 EPC |
Heating (kWh/m2)...................| 69.6 |.................| 70.0 |
Cooling (kWh/m2)....................| 38.4 |.................| 6.7 |
Auxiliary (Fan Energy) (kWh/m2)..| 41.6 |.................| 49.0 |
Lighting (kWh/m2)...................| 46.4 |.................| 27.8 |
DHW (kWh/m2).......................| 10.4 |.................| 13.1 |
Equipment (kWh/m2)................|46.0 |.................| 45.1 |
Total ...................................| 252.4 |...............| 211.7 |

EPC Rating ...........................| 109 E |...............| 136 F |

The only real difference is a lighting upgrade, all the fuels etc. are the same. So the simulation with the lowest energy and lowest carbon emissions gets by far the worst rating!

On a slight side track there was recently a good article in CIBSE about getting a much better rating through really extensive EPC surveys e.g. using lux meters and measuring actual U-values.

http://www.cibsejournal.com/general/hig ... gle-house/

We really need a good document that explains the methodology to clients, if EPC ratings are going to have a massive financial impact in 2018. It almost sounds corrupt if you say "pay us more for the survey and you get a better rating". This really all needs regulating (perhaps by defining different levels of survey detail) so assessors quotes can be compared fairly.


Ross

[RossThompson87]

Just as an update, I've stumbled across some research into this.

https://s3.amazonaws.com/co2e-documents ... 017_RG.pdf

These guys looked at 3500 EPCs and found that a really large number would get worse ratings on re-simulation.

Some even dropped by two rating bands.

Ross