BER Technical thread

...can I ask a general u-value question, because the BRE calculator I have doesn't have the option for the particular construction I want to get a u-value calculation for.

To wit: 102mm brick on 50mm cavity on 215mm hollow blocks (uninsulated) with 120mm warmboard to inside face.

Just looking for an indicative u-value of what that may be.

u value = 0.16

sydthebeat wrote: »

u value = 0.16

..thanks Syd

sydthebeat wrote: »

u value = 0.16

Agreed. Or invert the hollow block default (2.4 uninsulated) from DEAP table s3 and add the resistance of the other layers for a similar result.

GHER

Hi, I have a query about range cooker / boilers and range cookers that heat hot water only.

In Appendix B, 4.2 "Single burner range cooker/water heater. Some ranges provide a cooking function and some or all domestic hot water without providing space heating. Such a range can only be specified as a water heater if the water heating function can be provided independently from the cooking function. The efficiency is taken from Table 4a. If it is unclear whether cooking and water heating are independent, the range should not be included"

Surely this means that it should be ignored in Deap as having a water heating function, not completely ignored even as a room heater?????

Same query with B, 4.3 - "Single burner dry heat range cooker. This type is an appliance with a single burner that provides a cooking function. It is not included in DEAP calculations."

It is not included as a boiler but surely it's not completely ignored, even as a room heater? Whether it's solid fuel or oil, it doesn't need to be used as a cooker to heat the room so why would it be ignored as a room heater??

The reason I ask is because I was classifying the range cooker as a room heater when identifying rooms that were heated in a dwelling with inadequate heating. What's the logic behind ignoring it completely when it is quite clearly is capable of heating a room and doesn't need to be used as a cooker to do so???

I know it can't be classified as a room heater on it's own for primary or secondary heating energy efficiencies.

Thanks in advance to any answers.

descol

Sydthebeat
Would you mind letting me have the name and spec for your U value calculator - PM me if you wish
thanks
Descol

pm sent

GHER wrote: »

Hi, I have a query about range cooker / boilers and range cookers that heat hot water only.

In Appendix B, 4.2 "Single burner range cooker/water heater. Some ranges provide a cooking function and some or all domestic hot water without providing space heating. Such a range can only be specified as a water heater if the water heating function can be provided independently from the cooking function. The efficiency is taken from Table 4a. If it is unclear whether cooking and water heating are independent, the range should not be included"

Surely this means that it should be ignored in Deap as having a water heating function, not completely ignored even as a room heater?????

Such a range can only be specified as a water heater if the water heating function can be provided independently from the cooking function. The efficiency is taken from Table 4a. If it is unclear whether cooking and water heating are independent, the range should not be included

i read that as saying it shouldnt be "specified as a water heater" but it makes no mention of ignoring from a space heating point of view.

sydthebeat wrote: »

i read that as saying it shouldnt be "specified as a water heater" but it makes no mention of ignoring from a space heating point of view.

"without providing space heating" is stated in b4.2 when it doesn't heat rads. Otherwise, why not say that your electric cooker is a roomheater?

MOTM wrote: »

"without providing space heating" is stated in b4.2 when it doesn't heat rads. Otherwise, why not say that your electric cooker is a roomheater?

yeah correct, i was focusing on the wrong thing.

so im not quite sure then what GHER is asking.
If the cooker cannot provide space heating, then it shouldnt be considered a room heater. Seems logical enough.

blacktea

descol wrote: »

Sydthebeat
Would you mind letting me have the name and spec for your U value calculator - PM me if you wish
thanks
Descol

hi Syd, if i could also get a link by pm to that u value calculator it would be appreciated. Thanks, blacktea

...another curious question.

I got a call from BER assessor on the issue of Psi values. According to him, our (calculated and accredited by a Notified Body) figures are 'too low' causing him a problem in getting a particular build to meet Part L.

Could I get a laymans version of why a Psi value can ever be too low ?? Confused I am !

just checked, the lowest value that can be inputted is 0.0001

BryanF

By any chance does he mean the fabric results are to low (ie better than the backstop values) so the % of renewables will have to increase?

If you get my meaning...

Handsandtools

The real value will change, depends on moisture level in structure and time of the year. As far as I know there's no tests done on thermal bridges and Psi values depending on weather conditions in Ireland.

Handsandtools wrote: »

The real value will change, depends on moisture level in structure and time of the year. As far as I know there's no tests done on thermal bridges and Psi values depending on weather conditions in Ireland.

Incorrect.

Handsandtools

Is there any tests done?
Pressure difference in winter and summer causes structure to accumulate moist in it!

have a ridiculous situation here with a Prelim DEAP Part L assessment.

everything complies currently, standard oil, solar, HRV, and wood stove configuration.
air changes per hour rate = 0.12

if i make this 0.15 EPC fails
if i make it 0.1 EPC is fine but renewables fail.

so i have to tell the clients to make the build air tight, not to much, not to little, but just right... "Goldilocks" tight....

there are serious problems with these algorithims........

Rabbo

It all stems from the ridiculous renewables requirements. There's rumours going of them possibly reducing them.

Have you looked at the possibility of photovoltaics? I'm finding that it's much easier to achieve compliance with a small array and costing much less than equivalent tube setup

the selection of products is fine with the clients, they are very happy with solar thermal.

the problem i have with it is the link between energy demand and renewable input.

a solar collector on a new house is deemed to provide a significant lesser amount of energy when compared to an retrofit installation on an old house (with the very same ancillary arrangement {cylinder, pumps, orientation, population equv} etc)

this is simply wrong and fantastical

its ridiculous to have a situation where the more you make the dwelling efficient, the less the renewable source provides... becuase thats just patently not correct.

i know the 'Heat Pump' situation is up for change, hadnt heard anything about the renewable requirement.

sydthebeat wrote: »

its ridiculous to have a situation where the more you make the dwelling efficient, the less the renewable source provides... becuase thats just patently not correct.

^^^this.

We've had to recently manufacture a 'lower spec' wall specifically because of this, for a particular project.

This is just nuts. It flies in the face of everything we know about good building.

The more this goes on, the more likely people are to disregard the relevancy of BER altogether.

galwaytt wrote: »

The more this goes on, the more likely people are to disregard the relevancy of BER altogether.

i personally try to keep references to BER and DEAP (Building reg, Part L) separate as it leads to so much confusion... even with construction professionals

had quite a time the other day trying to explain to an engineer that he should be looking for a "preliminary DEAP assessment report" as part of his commencement documents and not a "provisional BER certificate" because the provisional BER certificate has nothing to do with building regs and doesnt show any compliance or not with Bregs.

on the DEAP calculations, having it go so far as to lower a wall construction u value in order to comply is simply farcical and, in my opinion, an indictment on the lack of real world understanding by the compliers of the algorithms.

sydthebeat wrote: »

the selection of products is fine with the clients, they are very happy with solar thermal.

the problem i have with it is the link between energy demand and renewable input.

a solar collector on a new house is deemed to provide a significant lesser amount of energy when compared to an retrofit installation on an old house (with the very same ancillary arrangement {cylinder, pumps, orientation, population equv} etc)

Is it a solar water heating.system or does it include solar space heating? The renewables contribution from the solar water heating is not going to change with different space heat loss parameters in DEAP.
What is the renewables contribution in this dwelling from solar and stove with each airtightness scenario?

MOTM wrote: »

Is it a solar water heating.system or does it include solar space heating? The renewables contribution from the solar water heating is not going to change with different space heat loss parameters in DEAP.
What is the renewables contribution in this dwelling from solar and stove with each airtightness scenario?

good point, i was of the incorrect opinion that it does.

the situation above still stands however, where a 'goldilocks' air tightness result is required to comply. The air tightness is really the only 'unknown' when doing these assessments so its interesting to play with them to see how different results affect the outcome.

In this particular assessment, i have bitten the bullet and specified the provision of a third solar collector to ensure theres no confusion on final assessment.

sydthebeat wrote: »

good point, i was of the incorrect opinion that it does.

the situation above still stands however, where a 'goldilocks' air tightness result is required to comply. The air tightness is really the only 'unknown' when doing these assessments so its interesting to play with them to see how different results affect the outcome.

In this particular assessment, i have bitten the bullet and specified the provision of a third solar collector to ensure theres no confusion on final assessment.

I've said it before and I'll say it again. If TGD L defined "reasonable" as a percentage and not an absolute this wouldn't be an issue.

THE DON FANUCCI

Right,
before i ask my assigned certifier i'll ask it here first;

I'm going starting a new build soon, and I want to know if you think this will comply with part-L regulation?

2,400 sq. ft. 2storey house,

100mm block, 100mm pumped insulated cavity, 100mm block walls,
sand and cement plaster internally (on the external walls).
100mm insulation under concrete floor
220mm moy metac in first floor joists and 220mm in attic joists.
sealed airtight tape around double glazed windows and doors.

wooden log only stove in sitting room with back boiler.
oil central heating also.

any other energy saving ideas I can add to this house that won't break the bank?

(I also have an open fireplace in other sitting room)

THE DON FANUCCI

Right,
before i ask my assigned certifier i'll ask it here first;

I'm going starting a new build soon, and I want to know if you think this will comply with part-L regulation?

2,400 sq. ft. 2storey house,

100mm block, 100mm pumped insulated cavity, 100mm block walls,
sand and cement plaster internally (on the external walls).
100mm insulation under concrete floor
220mm moy metac in first floor joists and 220mm in attic joists.
sealed airtight tape around double glazed windows and doors.

wooden log only stove in sitting room with back boiler.
oil central heating also.

any other energy saving ideas I can add to this house that won't break the bank?

I haven't done any deap/ber yet

(I also have an open fireplace in other sitting room)