Bugs and Requests

johntaylor · Posts: 52

I've been testing designbuilder and have a few bugs and requests:

Bugs
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1. After simulation if the sim graph is changed to annual to get the energy totals in the fuels graph, electricty and boiler energy are totaled correctly. **However the HVAC aux energy isn't totaled**.

2. The HVAC aux energy is applied only to heating and not cooling. Is this intential? It seems that both have aux loads.

3.There is a bug in the annual graph code if the simulation isn't run for a whole year. some of the graphs (temperature) are calculated as if they were run for a year instead of the period they were run for.

4. In imperial units the mechanical ventilation pressure rise is in PSI. The typical numbers would be fractional, but the input field won't display a fractional number. And the most typical unit for this would be inH2O not PSI.

5. In The heating design (perhaps other graphs, i haven't checked), with imperial units the bar chart show the numbers correctly scaled (-101 kbtu/h), but the table below is wrong (-101 BTU/h)

Requests
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1. I'd like the heating design tab to provide an option to include the internal gains and minimum solar gain of the weather file. That would provide a more realistic basis for calculating hvac requirement in efficient buildings and passive solar design.

2. I'd like to have a better interface to the crack template. Right now I'm using simple instead of calculated, even though the modeling is less accurate, because I have no quantifiable basis for selecting a crack template. It would be REALLY helpfully to be able to enter a ELA or ACH @ 50 PA, and have a crack template created to meet that real world data.

3. Multi year support would be nice. Sometime high mass designs need a year warm up time before simulation.

johntaylor · Posts: 52

More requests.

I was just looking at the evaluation graphs in HEED. Very Very Very useful. It would be nice to have more analysis views in designbuilder.

3D surface graphs are very useful for evaluating designs looking at whole annual simulations: month (x), hour (y), target variable (y). These graphs should be available for all components individually

A way to look at component gains/losses by element or group. For instance it would be very helpful to look a windows loss/gain graph with each of the window individually graph or graphed by oreintation group (north win, south win, west win, etc)

johntaylor · Posts: 52

more requests.

It would be very helpful to have schemes to compare design options. It would be very helpful to do graph comparisons of those schemes side by side.

It would be nice to be able to queue up several schemes to run. Even nicer if you could set up scheme variables for DB to run through a monticarlo set of options.

Also why is designbuild so slow. HEED is java based and still very snappy!

Andy Tindale · Posts: 1198 Location: Stroud

John,

In answer to your points:

Bugs

1. This should be fixed in version 1.2.0.041.

2. There was a problem with the old way auxiliary energy was modelled in Simple HVAC. It has now been changed so that the auxiliary energy consumption is defined based on the HVAC system type.

3. This bug is fixed.

4. Thanks for pointing this out - will change to inH2O

5. We are aware of this bug and are aiming to find a solution ASAP.

Requests

1. This is a difficult one because heating design calculations are traditionally carried out in the steady state and if solar and internal games are included in the steady state (as opposed to 8:00-18:00 say) then there will be an overestimate of their effect. There is no way we can easily include solar gains in heating design calculations. It may be possible for us to include some form of intermittent operation in a future version including internal gains as an option.

I suppose you could carry out a simulation using real weather data for the coldest week?

2. This is on our list - yes wouldn't it be great to be able to enter ACH @ 50 Pa and get an appropriate set of crack templates. I'll look into it.

3. Not sure what's required for this. Have you used EnergyPlus before with multi-year simulations? Has anyone else reading this post any experience?

johntaylor · Posts: 52

Andy,

thanks for the replies. Nice to know you are listening. I've surveyed many of the sim programs, and what nice about DB is its use of a more comprehensive simulation engine and modeling (& CFD soon I hope).

However, it is lacking many of the tools to truly evaluate the design, not just simulate. HEED & Ecotect do this well. Some of the tools that are important is design efficient buildings:

1. Annual 3D graphs of any feature ( see pic #1)
2. Graphing window gain/loss by orientation (N,S,E,W)
3. Visualize incident solar radiation on surfaces calculated over any period (see pic #2). Or on an annual overlay (pic #3)
4. Whole building shading analysis, even better if you can select by orientation (pic #4)
5. A key upgrade to shading analysis is to overlay onto the graph color coded indoor (or outdoor) temperature or comfort similar to the graph in pic #5
6. Better annual (or month by month) statistical views of room temperature and comfort, with an easy interface to step through the months (and fast updating of the graphs!) (see pic # 6)

johntaylor · Posts: 52

pic #2

johntaylor · Posts: 52

pic #3

johntaylor · Posts: 52

pic #4

johntaylor · Posts: 52

pic #5

johntaylor · Posts: 52

pic #6

Andy Tindale · Posts: 1198 Location: Stroud

Thanks for the graphics - I can see much more clearly what you are asking for now.

Regarding the slow simulation speed, I expect you are aware that the depth of calculations carried out by EnergyPlus is orders of magnitude greater than the simple calculations used in Ecotect and HEED and that this is why it takes longer. Hopefully the accuracy provided by the EnergyPlus simulations is worth the wait Smile

Having said that, there is plenty of room for improvement in EnergyPlus simulation speed and this is being addressed at our end by generating more efficient EnergyPlus input data and by the EnergyPlus development team by optimising the simulation algorithms.

We are also looking into the possibility of providing faster calculations using our own 'lumped parameter' simulation method for early stage design in the not too distant future.

Andy

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