Re: [EnergyPlus_Support] The eco roof simulation E+ example file

Design Builder is very user friendly- Im sure you can do it--From design builder help- http://www.designbuilder.co.uk/helpv3.1/#GreenRoof.htm

Green roof tab Materials Dialog

Green roofs can be modelled in DesignBuilder by creating a roof construction using a Green roof material as the outer layer. The green roof can receive water during the simulation from an irrigation system and/or fromsite precipitation (defined separately from the hourly weather data). The initial properties of the soil layer are defined on the Green roof tab of the Materials dialog.

Green walls can also be modelled though in this case the irrigation must be treated differently to roofs as walls will not naturally trap much precipitation.

Note that specifying a green roof material as the material for a component block will not work - these only use materials for their reflective properties.

Background

Use of green roofs (aka ecoroofs or vegetated roofs) is becoming increasingly common for both new and retrofit buildings. There is widespread recognition and a growing literature of measured data that suggest green roofs can reduce building energy consumption. The EnergyPlus Green Roof capability can assist developers and architects in assessing the likely magnitude of energy savings associated with various implementation options (e.g., soil type/depth, irrigation options, plant type). It provides a quantitative and physically-based building energy simulation tool that represents the effects of green roof constructions and facilitates more rapid spread of green roof technologies and make it possible to account for green roof benefits in state energy codes and related energy efficiency standards such as LEED.

The green roof model accounts for:

Long wave and short wave radiative exchange within the plant canopy,
Plant canopy effects on convective heat transfer,
Evapotranspiration from the soil and plants, and
Heat conduction (and storage) in the soil layer

The ability to track moisture-dependent thermal properties is not implemented yet due to stability issues in the CTF scheme, but is under development for use with the finite difference solution scheme made available in EnergyPlus starting in version 2. As implemented in EnergyPlus the green roof module allows the user to specify ?ecoroof? as the outer layer of a rooftop construction. The user can then specify various aspects of the green roof construction including growing media depth, thermal properties, plant canopy density, plant height, stomatal conductance (ability to transpire moisture), and soil moisture conditions (including irrigation). The model formulation includes the following:

Simplified moisture balance that allows precipitation, irrigation, and moisture transport between two soil layers (top and root zone).
Soil and plant canopy energy balance based on the Army Corps of Engineers? FASST vegetation models (Frankenstein and Koenig), drawing heavily from BATS (Dickenson et al.) and SiB (Sellers et al.).
Soil surface (Tg) and foliage (Tf) temperature equations are solved simultaneously each time step, inverting the CTF to extract heat flux information for the energy balance calculation. The detailed energy balance analysis and resulting equations, being rather complicated, are summarized here. The interested reader is referred to the FASST documentation cited herein for the complete development. The end result is a set of two simultaneous equations for temperature?one for the soil surface and the other for the foliage.

Green roof data

Height of Plants

The average height of plants in the green roof.

Leaf Area Index (LAI)

This is the projected leaf area per unit area of soil surface. It is a dimensionless number between 0.001 and 5.0. The tables below gives some typical values for LAI.

The table below is reproduced from Global Leaf Area Index Data from Field Measurements, 1932-2000

The table below is reproduced from the PhD Thesis of Chen Yu entitled The intervention of plants in the conflicts between buildings and climate - A case study in Singapore

Plant description	Mean Leaf Area Index (LAI)	Picture
"White flowers, spider lily"	3.07
"Pink flowers"	4.95
"Yellow green leaves"	3.75
"Dark green long blades of leaves/grass"	5.82
"Pinkish red flowers"	2.44
"Fern-like"	6.59
"Palm tree-like"	4.41
"White flowers with yellow center"	3.21
"Small yellow green leaves"	4.08
"Long big leaves"	5.28
"Orange stems and leaves for those which are taller"	2.15
"No special features"	3.32
"Light green edges with dark green center leave blades"	5.83
"Red yellow tulip like flowers"	3.04
"Large red leaves"	2.33
"Dark green leaf blades"	~0
Tree	1.69
Palm tree	2.37

Leaf Reflectivity

The fraction of incident solar radiation that is reflected by the individual leaf surfaces. Solar radiation includes the visible spectrum as well as infrared and ultraviolet wavelengths. Values for this field must be between 0.1 and 0.4.

Leaf Emissivity

This field is the ratio of thermal radiation emitted from leaf surfaces to that emitted by an ideal black body at the same temperature. This parameter is used when calculating the long wavelength radiant exchange at the leaf surfaces. Values for this field must be between 0.8 and 1.0 (with 1.0 representing ?black body? conditions).

Minimum Stomatal Resistance

This field represents the resistance of the plants to moisture transport. It has units of s/m. Plants with low values of stomatal resistance will result in higher evapotranspiration rates than plants with high resistance. Values for this field must be in the range of 50.0 to 300.0.

Max volumetric moisture content of the soil layer (saturation)

Maximum volumetric moisture content of the soil depends on the properties of the soil and in particular the porosity.

Min (residual) volumetric moisture content of the soil layer

The minimum possible volumetric moisture content of the soil layer.

Initial volumetric moisture content of the soil layer

The volumetric moisture content of the soil layer at the start of the simulation. The moisture content will be updated during the course of the simulation based on surface evaporation, irrigation and precipitation.

Jeremiah D. Crossett | Senior Analyst | Phase Change Energy Solutions

120 E. Pritchard St. | Asheboro, NC 27203 | Mobile 503-688-8951

www.phasechange.com

On Sun, Sep 9, 2012 at 8:42 PM, fong haibo <fongkwt@xxxxxxxxx> wrote:

Dear Jeremiah,

Thanks for your suggestion. Let me learn the Design Builder first and see if I can handle it.

Have a good night.

Best

From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of Jeremiah Crossett
Sent: Sunday, September 09, 2012 8:03 PM

To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: Re: [EnergyPlus_Support] The eco roof simulation E+ example file

Sorry to assume you had never actually opened E+.. I would advise you to download the one month free version of Design Builder- it has the ability to call any surface a green roof/wall. Use it to crate your IDF and read the detailed documentation of the E+ ecoroof model they have within their help option. By the end of the free month you should have been able to create a few IDF's that you can use as templates..

Best regards

Jeremiah D. Crossett  | Senior Analyst  | Phase Change Energy Solutions

120 E. Pritchard St. | Asheboro, NC 27203 | Mobile 503-688-8951

www.phasechange.com



On Sun, Sep 9, 2012 at 7:56 PM, fong haibo <fongkwt@xxxxxxxxx> wrote:

Thanks for the quick answer.

I know the basic energy simulation through E+. as well as use the IDF Editor to get the special buildings I need. Now, I want to do the energy simulation for a building which has green wall (vegetation layer) attached on the building façade. So, I am still not clear how to modify the component to satisfy the characteristic of green wall. Could you tell me anything you know about that ? (The wall only has the W/m h)

By the way, I have already watched the video you attached to me. But I am not sure which software the video is talking about? Revit, Openstudio or others?

Best

From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of Jeremiah Crossett
Sent: Sunday, September 09, 2012 7:02 PM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: Re: [EnergyPlus_Support] The eco roof simulation E+ example file

Hopefully Dr YI is not offended, by my answering this- but please:

Watch the intro videos about how Energy Plus works http://www.youtube.com/watch?v=qfqEXN-icQA (there are a few on you tube but this is a good starter)

Do the intro exercises (these will give you a practical understanding
Search for the item you want to model in the documentation that comes with Energy Plus

The attached file comes with energy plus> example files>ecoroof Orlando
It is possible to build any facade you want in energy plus, but I am unsure what you are talking about with regards to the import.

I started with modification of IDF files to model systems rather then buildings and was able learn the basics in about a month, and got very comfortable with most functions of the software within 2 years.

Best regards

Jeremiah D. Crossett  | Senior Analyst  | Phase Change Energy Solutions

120 E. Pritchard St. | Asheboro, NC 27203 | Mobile 503-688-8951

www.phasechange.com



On Sun, Sep 9, 2012 at 6:37 PM, fong haibo <fongkwt@xxxxxxxxx> wrote:

Dr Li,

Could you send me the example file for the green roof (eco roof)?

Is this possible to use software to create a building facade with specific thermal characteristics, and import to E+ as an component to do energy analysis?

Thanks

Best Regards
Haibo