DEAP vs PHPP

AidanD12

I'm in the process of finalising my plans for submission to planning. I'm aiming for a low energy (low running cost) house and want to hit that sweet spot of spending the money in the right areas to give me the best savings. Now I'd like to validate the design is optimal in terms of energy (ie right proportion glazing/shading) and also decide what the best heating combination would suit as well as the spec of the materials (glazing, insulation etc). Everyone seems to have different views so would be good to see hard numbers to make informed decisions.

So after some helpful tips here and others I was under the impression that a provisional BER would answer my questions (although I don't think its a requirement yet for Cork co co). However having chatted yesterday with an assessor I'm not so convinced, as it seems to be more directed towards making sure you are within regulations and giving you the rating (eg A3) rather than really optimising the build. Of course I want to meet all the regulations although I'm really not concerned about the label (A3, passive etc) but rather getting the best value for money spent on the build. I downloaded the DEAP last night and played with it for a while and it seems pretty intuitive and I think I could do a lot of the grunt work myself and do the trial and error approach of just playing the numbers of the different components to maximise the rating but of course since no costs (installation or running) are input it mightn't really give me what I'm looking for. Am I bit naive here or would it just be better to get an assessor to this for me? I know getting a PHPP done would be an extra cost (700-1000 compared with 250 for BER) and is a lot more detailed (of course it also doesn't include the costs) but do people think its worth it and the output would be that much more effective than DEAP in helping with the decisions I need to make and hopefully have a better result. If so maybe someone could pm me a good PHPP assessor in Cork as the BER guy I spoke with knew very little about it.

Thanks for taking the time to read the post and sorry for the long winded explanations!

sydthebeat

DEAP is a tool used for general comparisons of like with like.

PHPP is much more specific to the individual.

Obviously PHPP is a much more useful tool when trying to optimise budget on materials and technologies etc. But that usefulness comes at a cost.

A provisional DEAP assessment could take a day to complete
A PHPP assessment could take a week.

getting best "value for money" is very relevant to your build budget and your projected running cost budget. For example, can you afford the bolt-on technologies at construction stage, or if not, can your running cost budget absorb the shortfall....

AidanD12

Thanks sydthebeat,
ya everything is a balancing act time/cost/scope. I'm happy to front load a cost if I can see it paying back in a reasonable time. Do you reckon the PHPP falls into this category and is it of more real value than the BER? Do you think an inexperienced person could use the DEAP software to good enough effect? I just have the feeling that it won't yield enough information I don't already know to make informed decisions.

BryanF

AidanD12 wrote: »

Do you reckon the PHPP falls into this category and is it of more real value than the BER?

the BER is no where near as accurate as PHPP - hence the difference in input time and therefore associate cost

Do you think an inexperienced person could use the DEAP software to good enough effect?

if you have the time yes, but i guarantee you'll be here for the next month asking questions and then you will have to get an assessor to submit the BER anyway. deap is a poorly thought out assessment tool (for complaince with part L and the committed 60% reduction on 05 co2 levels) - phpp is a more interactive design tool - still flawed but must better the DEAP

I just have the feeling that it won't yield enough information I don't already know to make informed decisions.

if nothing else it will force you and your design team to really look at the heat losses from elements and their interfaces, provide a more detailed look at how to balance your window spec and give you the kwh/m2/y figure you need to look at your heating system.

MENACE2010

Hi
Same here we have the design of the house, now it comes to the final decisions. I wondered if PHPP is worthwhile to do , so far I got one quote and the cost is quite staggering. I would like to hear of examples where PhPP made a difference and saved cost the last thing I need and want is to build and over engineer on the heating or on other elements in the house

most of the glass in the house is south west facing, and we are aiming for u value on the walls of 0.15 or better

- I'm glad to share the house design in a PM


if there are people out there who can help here with the following

- some examples of where PHPP worked out as a saving grace..
- PM me with some contacts of people who can do this for me

Thanks

BryanF

MENACE2010 wrote: »

the last thing I need and want is to build and over engineer on the heating or on other elements in the house

thats the point of phpp - the irony here is that DEAP ( BER) indicates that CO2 saving can only be made by installing renewable technologies ,when its limiting the need for a heating system that should be advocated. In-lieu of a better assessment method/ software package phpp is imo the way to go -as a design tool.

here's a few studies from the UK,

the Denby Dale one is well documented http://www.greenbuildingstore.co.uk/news--passivhaus-code-for-sustainable-homes.html

(NOTE: SAP = BER)

the AECB link has a great comparison document, the following is a small section of the conclusion:

Overall, SAP plays down the significance of insulation and airtightness, and assumes high levels of internal gains, leading designers to believe they have reached a sensible lower limit on heat loss when in fact they have not.
7.10 SAP does not provide well for passive solar design in that windows and shading are not modelled in detail and the effects of thermal mass are not included. In particular, using SAP as a model does not permit the use of efficiency measures in electricity use, such as efficient pumps. Where a set level of carbon emissions is to be met this rules out efficiency measures in favour of electricity generation technologies such as photovoltaics.
7.11 SAP was developed in the 1980s from a study of homes with relatively poor levels of insulation and therefore high levels of heat loss. It is not precise about areas that become critical in very well-insulated dwellings where a heat loss of, say 3kWh/m!.yr, represents one-fifth of the total allowed for space heating of 15 kWh/m!.yr in a PassivHaus standard dwelling. PHPP was created to assist with the design of comfortable, healthy homes using the minimum amount of energy. These divergent histories are the reason for the fundamental differences in the outputs of the two models.
7.12 The estimation of CO2 emissions in SAP is significantly lower than in PHPP, even allowing for differences between the electricity systems in the UK and Germany

http://www.aecb.net/PDFs/Combined_PHPP_SAP_FINAL.pdf

There are significant differences between SAP and PHPP, so that SAP should not be used to make comparisons with Passive House or CarbonLite standards. The PHPP assumes lower internal gains than SAP (2.1 W/m2 vs. 6.7 W/m2 and 7.7 W/m2 for the 2007 detached house and mid-floor flat respectively) and therefore gives a higher space heating energy demand. Other differences between PHPP and SAP include the use of local climates and the treatment of air permeability and thermal bridges

p27 http://www.scotland.gov.uk/Resource/Doc/217736/0091333.pdf

simply put DEAP does not reward good design. PHPP is not perfect - its just a stepping stone to where we need to get to in building sustainable homes, but closer than DEAP thats for sure.