Self build - planning conditions

[BrianWg]

I have planning approval for a "Erection of a detached two storey dwelling with basement with car parking spaces and new vehicular access"

A condition is "Prior to the commencement of development, an Energy Statement incorporating 'as-designed' Standard Assessment Procedure (SAP) outputs must be submitted to the Local Planning Authority and approved in writing which demonstrates how the proposed dwelling/s will apply the Mayor's energy hierarchy (use less energy, supply energy efficiently and use renewable energy) to achieve at least a 35% reduction in CO2 emissions below the target emission rate (TER) based on Part L1A of the 2013 Building Regulations and at least a 10% reduction in total emissions (regulated and unregulated) through on-site renewable energy generation. The development should exceed the minimum Part L1A emissions standards through energy efficiency measures alone. The development shall be carried out in accordance with the approved details and thereafter retained. Reason: To comply with Policy 31 of the Sutton Local Plan 2018. This condition is required to be precommencement to ensure that these details are considered at a early stage of the process and the required details are an integral part of the construction." 

 

I have had a SAP assessment on the design construction - but my SAP assessor has emailed me "

The current documents show the nominal 2013 dwelling against your design and currently with the modified documents I sent to you, the dwelling achieves a 5.8% reduction in carbon emissions. This can be see using the Code For Sustainable Homes document. The water calc does not have an impact and the as designed air tightness target of 0.3 is already included (0.3 is very low) You don’t have a choice regarding renewable energy systems, these must be introduced to the dwelling. In my experience, the only way to achieve the 35% reduction is with a heat pump (either air source or ground source) and with solar PV on the roof. We can explore a biomass boiler to see how it performs.

 

They are asking for an energy statement to be written demonstrating the how the design meets the requirements. This is a lengthy process which I can do for you or you can do yourself. My price to write the statement is £500. (no VAT to add)

 

Ouch! - can anyone explain what this means to me? Is there any chance I could meet this condition without an ASHP - a ground source heat pump is out of the question as I have a very limited footprint for the plot

 

6 -170A Banstead Road design stage-CSH.pdf 6 -170A Banstead Road design stage-PredictedEPC.pdf 6 -170A Banstead Road design stage-SAP Input.pdf 6 -170A Banstead Road design stage-CheckList.pdf

[PeterW]

So reading that, you have to include Solar PV anyway - is it in the design ..?

 

ASHP isn’t an issue - get the UFH and rads designed right and the insulation levels sorted and it should be fine. 
 

Also worth revisiting the windows - those don’t look good values for the overall openings but bank the savings.!

 

Also, has he done the initial DER on the bare minimum values to get a pass ..?

[Mr Punter]

This is a standard condition.  Look at other planning applications for Sutton and see how they have discharged the condition.  PV is an easy way to comply but your energy assessor should know that. Biomass gains almost nothing so maybe your assessor is not so good.

[nod]

We had similar conditions 

PV being one We both hate the look of solar panels and a projective payback of 17 decided not to fit PV

While this was an issue for the original Sap company It wasn’t for an online company 

£120 for the final Sap report 

Just another bit of paper 

[Onoff]

24 minutes ago, nod said:

We both hate the look of solar panels

 

+1 but there are some in-roof systems that sit flush with the (ideally) slates, that are dare I say, pretty good looking.

 

(Imho).

[nod]

Perhaps on the next

We has so many restrictions by British Heritage to blend the property in with the old farm 

Even not allowing walls and fences 

Or the type of chimney pot we used 

It just seemed odd to put solar panels on the roof 

[Conor]

Go back to the assessor and see what happens when you upgrade insulation to about 0.15 and put in triple glazing. This is kinda what we should all be doing as a min starting point before thinking about heat sources and power generation. 

[the_r_sole]

do you not have an architect/designer talking you through the options for the energy performance?

your fabric u-values aren't great at all, sometimes adding a woodburner as secondary heating can get you a bit of a bump, as can tweaking the air tightness... but you really need to be looking at some kind of heat pump to get the target. One that surprised me recently was waste water heat recovery, that's something I'm going to put in everywhere from now on!!

[Moonshine]

4 minutes ago, the_r_sole said:

your fabric u-values aren't great at all

 

Any in particular stand out? to me floors and roof seems to be too the weak areas? basement at 0.2, and roof at 0.16?

 

[the_r_sole]

3 minutes ago, Moonshine said:

 

Any in particular stand out? to me floors and roof seems to be too the weak areas? basement at 0.2, and roof at 0.16?

 

 

 

All of it could be upped (or downed!) quite easily, what construction are you using?

Windows and doors would give you the biggest bang for buck upgrade, do you have any fixed panes or anything? easy/cheap to put them as triple glazed...

[Moonshine]

55 minutes ago, the_r_sole said:

All of it could be upped (or downed!) quite easily, what construction are you using?

 

Plan is

 

External walls - rendered 100mm block, 150mm full fill (0.032) batts, 100mm aerated block (0.011), dot/dab plaster board: U-value ~0.17

 

Roof - warm roof with 150mm PIR insulation (0.022): U-value ~0.13

 

Majority of floor - block and beam with 150mm PIR insulation (0.022) under screed: U-value ~0.12

 

Not sure of U value of windows but 1.4 seems to work to get a SAP of 85 among other things

 

I want to make sure that this is insulated enough to use a ASHP with UFH.

 

I see what you mean about the  waste water heat recovery, adding one for two showers bumps the SAP up by 1 point.

Edited September 22, 2020 by Moonshine

[Mr Punter]

You get loads of credit for reduced thermal bridging.  You can get proven lower psi values with Keystone Hi-Therm+ lintels and apparently the best value way towards your SAP targets.  If you go ahead with them, order them well in advance as they are not a stock item.

[the_r_sole]

33 minutes ago, Moonshine said:

 

Plan is

 

External walls - rendered 100mm block, 150mm full fill (0.032) batts, 100mm aerated block (0.011), dot/dab plaster board: U-value ~0.17

 

Roof - warm roof with 150mm PIR insulation (0.022): U-value ~0.13

 

Majority of floor - block and beam with 150mm PIR insulation (0.022) under screed: U-value ~0.12

 

Not sure of U value of windows but 1.4 seems to work to get a SAP of 85 among other things

 

I want to make sure that this is insulated enough to use a ASHP with UFH.

 

I see what you mean about the  waste water heat recovery, adding one for two showers bumps the SAP up by 1 point.

 

what happens if you put the windows and doors in at 1.2?

 

the thing is, the SAP rating doesn't matter for your planning condition, you just need to show the percentage improvement over the TER