The results look reasonably close to those expected but that you haven't
reached the far enough down the curve yet to see it stagnating? Either that
or there are some other factors in the model which become more less
significant with reducing U-value?

*Dr Claire Das Bhaumik CEng FCIBSE*

*Partner - Inkling LLP*

e: claire at inklingllp.com

t: 07950 282800

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Hi Mayank,

I recommend opening up the SIM file (you can do this by going to Tools -> View Simulation Output) and looking at the LS-C and LV-D reports. In the LS-C report you can find the contribution to the peak heating and cooling loads that come from the walls. From this you should be able to figure out how the wall conduction is changing as a fraction of the peak loads as you decrease the wall U-value. In the LV-D report (scroll to the very end of it) there is a summary of the U-values for each exterior surface. This might be a good place to look to make sure that the effective U-values that eQUEST is simulating are matching up with your expectations of what the U-values should be.

I would agree that the energy savings should saturate at some point.

All the best,
Dan

?
Daniel Knapp, PhD, PPhys, LEED? AP O+M
danielk at arborus.ca

Arborus Consulting
Energy Strategies for the Built Environment
www.arborus.ca
76 Chamberlain Avenue
Ottawa, ON, K1S 1V9
Phone: (613) 234-7178 ext. 113
Fax: (613) 234-0740

As a standard rule, please post the eQUEST file you are using to get these results, so we can see what other inputs may be affecting the outputs.

The reason for using an energy model is to capture the interactive effect of all building components when one item is changed, so the intuitive answer may not be the actual answer in any one specific scenario.

Regards,

David Griffin, BEMP
Senior Energy Analyst

ARCHITECTURAL
NEXUS
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Salt Lake City, UT 84109

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Direct 801.924.5028

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Dan,

Very good point! I didn't even think about this, i.e., that the plot was against
conductance and not resistance.
Therefore, I would conclude that eQUEST is behaving properly.

Joe

Joe Huang
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After seeing Nick?s comment I thought I would add my 2 cents just being in Alaska and constantly dealing with insulation issues.

The winter obviously puts high demands for heating and ventilation and I think every building we?ve upgraded for energy efficiency has seen substantial improvements in energy savings.
But many of our clients insist on ?more insulation is better? in arctic conditions without really understanding the effects over an entire year.

On some projects I?ve seen R-80+ systems with 18? wall buildups. Not to mention R80-90+ roof buildups (14?-16? thick) which obviously improve the overall heating performance ? especially given our heating systems are typically operating more than 6 months out of the year.

But there is a tradeoff.

We typically get around 4-1/2 months of 60-90 degree weather up here. This puts a high demand on cooling systems during this period. You can easily end up with a building so heavily insulated that even in the mid 60?s outside temp range the cooling system may need to operate unless all the doors and windows were opened up? which isn?t always possible because of security reasons.

The buildings become too efficient at retaining heat to the degree that the cooling demand is higher to basically fight the building during summer months to maintain temp setpoints.

Also, Many buildings in Alaska do not have cooling systems so when you increase R-value and U-value to a certain threshold you are in some ways ?biting the bullet? with regard to adding appropriate ventilation and cooling systems capable of cancelling out the heat buildup in warmer weather (which offsets X dollar amount of energy savings provided during the winter months).

Fortunately, the end result in Alaska is usually a net cost savings just because heating costs in Alaska are so ridiculously high given most buildings use fuel-oil.

However, in theory, if you were to cut the cost of heating up here to a certain threshold the cost of cooling the building would eventually be higher than the cost of heating it in the winter months. At which point I imagine someone doing the classic face-palm.

-Chris