Ecotect 02 | Shading (II)

WHAT IS THE SITE/OBJECT OBSTRUCTION/OVERSHADOWING? (II)

In this tutorial, continued from last session in checking the site’s obstruction/overshadowing. You could use the same example file as in that one (link).

We would like to understand how surrounding buildings would affect our site using shading mask overlaid on a sun path in order for us to start the design process. What we can check for with overlaid sun path diagram . .

- Any shading from surrounding buildings already? (E.g. we might locate some functional uses there without having to create a new shade).

- Any exposed area? (i.e. very hot in summer time and therefore extra shading is critical).

- Implication – building orientation, glazing placement, or other functional allocation in which this information could be useful for

HOW-TO

We’ll create a representative point on a site to check for obstructions – This is similar to when a person takes a fisheye camera (which has a 180 degree field-of-view), place it at one location on a site looking up and take a photo of the hemispherical sky dome.

1 | CREATING A POINT OBJECT

In 3d editor, click on point icon and click again to place it on a site. You can select a center of your site as a starting point (can be on any zone). It would be easier if you create point from plan view (View > Plan or hit F5).


A point will be visible in both 3d Editor and Visualise view.








2 | CHECKING FOR OBSTRUCTION USING OVERLAID SUN PATH

Make sure a point is selected.

Go to Menu Calculate > Sunpath Diagram.

A sunpath overlaid with shading from surrounding building would show up. This is a view from your site looking up to the sky – similar to what a fisheye lenses would see but the obstructions will be grayed out.















3 | SEPARATING ZONE & SHADOW COLOR

From step 2, we can see that the overlaid shadow mask is in the same color, and that is gray, which is a default shadow color in Ecotect. It would be more informative in some cases to separate the surrounding buildings in different zone (layer) and make it case different shadow color.

First, go to Zone management tab on the right, you’ll see zones labeled obs_xxxx. This is for all the surrounding buildings in each direction. Click ‘zone management’ button at the bottom. Zone management window shows up. There are many parameters you can edit within each zone.



Use a different color for each obstruction zone. Then, you can change each zone’s (layer) color for easy visualization. The 3d Editor view would by default show you the zone color.






Under Visualise tab, the objects can be displayed using zone color as well. Under visualize tab setting, change the ‘Surface Display’ color to Zone Color.




Based on this chart, optimal shading is critical on the south side even though we have some obstruction but those houses only block diffuse part of the sky but not the sun which is the major source of heat gain into a building.



Analysis

The overshadowing in pink shows that we have taller building on the east so it blocks some of the morning sun all year long. This is good for locations where shading is required all year because this means that we might be able to locate some uses on the east side without having to create a lot of shading.

Overshadowing from north and south sides (yellow and green) are from lower obstructions, allowing some diffuse light from the sky to come through.

Towards the west (orange) which is critical for afternoon use, at later hours, there are some shading from nearby buildings.


An important thing to note is that this shaded mask only represents the overshadowing from the point that you have placed on your site (in this example, in the center) and may not apply to all areas of your site since the shading will vary depend on where you’re at. You can move the point to other places on your site or creating more points, especially if the site is large, to check for potentials and limitations of the site at different locations in terms of overshadowing.




Note:

This is only an initial test on a blank site. Conditions change when you start to put a building on-site. A 2-storey vs a 5-storey building has different exposure to the sun and different overshadowing pattern from surrounding buildings. Once you have some design options with varying heights, it can be useful to transfer it to Ecotect to see how the shading requirements would change under different massing options.

Ecotect 02 | Shading (I)

SHADING CONCEPTS

Shading is an important component to energy efficient design, especially for climates which require a lot of cooling and clear sky prevails. This is because the sun is the primary source of building envelope heat gain. For other locations where there is a mix of heating and cooling needs, the goal for shading would be to prevent heat gain from direct sun in summer while allowing for passive solar heating in winter.

Example design questions that require shading analysis . .

•What is the site limitation in terms of obstruction?
•What is the optimum shading for a particular window?
•Which shading options are better for preventing direct sun?

In this tutorial, we’ll cover these topics:
- Read and understand sun path and shading mask
- Check for obstruction onto site or object
- Use shading design wizard as a starting point to design shading
- Understand parameters related to shading design and analysis


WHAT IS THE SITE/OBJECT OBSTRUCTION/OVERSHADOWING? (I)

This tutorial requires some basic knowledge of using Ecotect
Example Files: 01_site_analysis.eco



This is a blank site in residential area. The weather file now is Hong Kong, China; the weather file should come with your Ecotect package. If not, you can select any location of choice. A site is oriented with longitudinal sides facing east-west. The north icon in 3d editor view shows the orientation.

If you want to change the orientation of your model, you don’t have to rotate the whole model. Just go to Project tab and change the azimuth angle. Then, recheck in 3dEditor tab to make sure the orientation is correct.



First, we can check the overshadowing from neighbor buildings by clicking the ‘shadow range’ function under the Shadow Settings tab on the right. By selecting 3 representative days: summer solstice (Jun 21), equinox (Mar/ Sep 21), and winter solstice (Dec 21), we can check out the pattern of overshadowing throughout the year from surrounding contexts onto a site.



For example, in this setting, Ecotect will track the shadow from 12pm to 6pm, every 30 minutes.

In general, we check for overshadowing at 3 representative dates: Summer Solstice, Equinox, and Winter Solstice. You could also separate your analysis between morning and afternoon for more convenient analysis on what's happening to the site throughout the day and how to best zone the building's functional uses to fit the shading pattern.

With Ecotect, shadows from different massing layers can be toggle on/off to show the effects from different design options or before-after scenario.

Ecotect 01 | Tips for File Import

Although Ecotect allows for some modeling tasks but it’s typically an easier workflow for designers to use Ecotect’s import function to prepare the input file for Ecotect analysis instead of recreating the model from scratch. Many design firms, during design phase, designers might go for convenient tools like SketchUp to model the buildings since the form can be easily manipulated.

Ecotect allows for many file types to be imported but mostly .dxf or .3ds files are used.

Import process

File > Import > 3d CAD geometry

Import window will pop up with many options you can select. Important checkpoints are

Scale: For scale conversion between different programs. I’ll mention this issue later on.

Auto-Merge Triangles: The program will merge triangulated surface into rectangular ones to reduce the number of objects from the import process. If your model is complicated, this process can take up to hours (- and Ecotect kind of freezes during this time – so you can’t do anything with it but wait until it’s done). If you want to kill this process, there’s no other way but the classic Ctrl+Alt+Del!

So, for a large or complex model, it might be best to leave this box unchecked since you can always merge coincident triangles from the modify menu later on.

You can choose not to import some layers at this window also. It’s best to keep a small but workable file size (depends on your design question) in Ecotect since it uses quite some memory when running the analysis and the larger the file, the slower the simulation run.

For more details, use keyword ‘import’ under Ecotect’s Help section.

Ecotect Import Window

Modeling Programs:

AutoCAD

- Can be modeled as 3d object or extrusion
- Explode model before saving the file to .dxf format
- Saved file should be R12 dxf (anything lower than 2000 should be fine), otherwise Ecotect will not recognize it.
- If CAD model is in meter, in Ecotect import box, use 1000 for scale since the default unit for Ecotect is mm.

SketchUp

- Export > 3d Model
- Choose file type (For Ecotect, you can use .dxf or .3ds)

.3ds

- Gives you some useful options like separating layer based on SketchUp layer or materials (- dxf does not have this option). In the image below, a SketchUp model has 3 materials assigned to it and one default material. The model was exported to a .3ds with the option ‘by material’. In Ecotect import box, these materials can be grouped by pen number and you can then assign each one to different Ecotect layer (zone) and material.

It’s good to have a proper layer or material setup in your SketchUp model so that your Ecotect model can be easier to work with. Grouping objects in SketchUp doesn’t have any effects when importing the model into Ecotect in a .dxf or 3ds format.
If you have all objects in one layer (‘zone’ in Ecotect), separating object layers from within Ecotect can be quite a tedious task.

- In Ecotect import box
- Use 1 for scaling factor if SketchUp model is in mm
- Use 1000 if SketchUp model is in m
This is a fairly simple conversion but some programs, during Ecotect import process, works differently (like 3ds Max, for example).

Revit

- Export model as polymesh/ACIS solid so Ecotect can read it

3ds Max

- 3ds Max export for .dxf and .3ds does not have options to export by layer or material so Ecotect import box read the exported file as each item instead.

For example, if your Max file has 4 objects (box 1 – 4), Ecotect import box will separate each object to different item, namely box 1 to box 4. Still, you can set it to be on desired Ecotect zone or material.

- For 3ds Max file unit of m. or mm., when you import to Ecotect, conversion scale of 1000 has to be used anyway for Ecotect to have a correct unit.

Check model unit

After importing the model, you can use a measure tape to measure the model dimension to make sure it’s a correct scale before running any analysis. If the scale is wrong, you can re-import the file. Although Ecotect has a scaling option that you can use but the result doesn’t always turn out as expected, especially for complex model so I think it’s more efficient just to re-import the file with a correct conversion factor.

Optimize your model

Sometimes, imported file will have a lot of unnecessary lines which takes a lot of space and increases simulation time. You can check the file properties in the import box to see how many polygons or lines your file has and you can choose not to import that layer. Still, if you have to import all, there is an option in Ecotect that you can use to delete these lines and reduce your file size.

Go to Select > Element Type > Line

Ecotect will select all the lines in your model and the number of objects selected will be displayed on the lower left corner (e.g. 1400/4000 – means it’s selecting 1400 objects out of 4000 objects in your model)

In the export process from modeling program, some programs give you the option to export only surfaces and not lines. For SketchUp, for a 3ds, you have the option not to export stand alone edges and for a .dxf you can uncheck exporting edges to reduce the lines for Ecotect file.

Climate Analysis with Weather Tool | 02

For this session, another analysis function of Weather Tool: Optimum Orientation, will be discussed.

Weather Tool’s Optimum Orientation Analysis (Solar Position tab > Best Orientation)

When you use Weather Tool’s optimum orientation analysis function, the program would already define some defaults for 3 months peak overheated and underheated period, based on a weather file. Then, a fictitious surface would be rotated 360 deg. to check for initial incident solar radiation. An optimum orientation is one that receives lowest radiation during 3 summer months and highest in 3 winter months.

Default options for hottest and coldest months based on selected weather file

So, if you go with the defaults, you would assume that you’re going to use those months for the calculation. If you change the input months, you’ll notice that the optimum orientation is changed. This can be an issue for some locations like Thailand where you have only overheated months almost all year round. If you go with the defaults then the result could be misleading. For a very hot and humid climate, for example, Bangkok, you have to uncheck the underheated months and only specify the overheated months based on the weather file (kind of a judgment call on which months to use – better to check monthly or hourly temperature data).

After you get the optimum orientation, actually an orientation which differs by 10 deg. might not be that much of a difference in terms of incident solar radiation. You can check on this by clicking “Solar Position” button again and use a slider bar to check for incident solar radiation at different orientation.

Optimum Orientation Analysis screenshot

Solar Radiation screenshot (after optimum orientation is calculated)

Caveats

Since this orientation analysis is done in Weather Tool and the only input is a weather file, this means it has not considered the impact of neighbor building’s overshadowing or functional uses of a building at all. This is suitable for early design phase where you just want to have some ideas on how to approach a project based on the climate. Also, this result could be applicable for envelope-dominated building, while for internal load dominated building, this will affect the heat transfer at the building on the perimeter zone.

For a blank site in largely undeveloped area, then, some of the analysis derived from Weather Tool can be reasonably applied. Further analysis should be done if you’d like to test the impact of neighbor building or when you start to model your building. This will require other software tool such as Ecotect.

Climate Analysis with Weather Tool | 01

Weather Tool 01

This is an excerpt from a Weather Tool training note I created a year ago. (Originally posted on our previous green dwell blog but now all the contents will be moved here.) Although it is not meant to be a full tutorial set but I hope it can be useful for anyone who wants to run some climate analysis before conducting the design. There are many websites which offer Weather Tool and Ecotect tutorials so for this blog, I wanted to focus more on the application side – like how you’d look at the graphs and use it to inform your design process.

Climate analysis is an important process for green design and usually we just go online and extract some information out of a bunch of tables and texts. Some software can help us to link those tables to our design thinking process by using nice and informative graphics. Some tools that you can check out are Weather Tool, Climate Consultant, and Meteonorm.

Weather File

Weather Tool is quite easy to use, all you need is a weather file that contains average data of the weather for a specific location for several years. This can be downloaded from Ecotect website (.wea format) or from EnergyPlus website which would be in a .epw format and you can use Weather Tool to convert it. There are 2 methods in general to convert EnergyPlus weather file (.EPW) to a .WEA format. The first one is to use Weather Tool and the second method is to use EnergyPlus. The results might be different due to different averaging methods.

Even though the weather file is generally derived from a reliable source since the data obtained from a weather station; cross-checking can make sure the weather data you have is valid and can really assist your design decision-making.

Function

Weather Tool has 2 functions – visualization and analysis. For visualization, basically it just displays the information contained in a weather file like temperature, humidity, solar radiation, etc. Analyses are optimum orientation analysis and passive strategies analysis through a psychrometric chart.

Climate Consultant vs Weather Tool: passive strategies analysis

Documentation available on the analysis function of the program can be found in the program’s Help section. Personally, when I use the passive strategies analysis function, I usually go with Climate Consultant instead because I can’t find background information on the program’s calculation method for this.

Weather Tool vs Weather Manager

Weather Manager is a climate analysis program that comes with Ecotect. It is very similar to Weather Tool except for the Psychrometry and Solar Position functions that cannot be performed with Weather Manager. Weather Tool needs a separate license. If your version is a trial one, it won’t allow you to save the file. When you have Ecotect license, Weather Manager can be used to convert and save the file. Then, you can use Weather Tool for the analysis part (you can still use the ‘copy graph to clipboard’ function).

Home Design Trend 2011

Green is a Must, not a Trend . . .

We all hear the term “green” or “green building” quite frequently last year as green topics seem to gain a lot of attention from the media in every field. For us here at GreenDwell, we generally do not think of the term “green” as a trend until we were approached by one magazine with a question on whether we think green will still remain a trend this year. We look at this question with great interest; if you went to d&D Magazine event before year end, you may have already known how we have responded to this question.

Here we summarize our view to this question in case anyone is interested to hear what we have to say and may wonder how long this “trend” would last for Thailand. Even more, the word “green” also exists in our name and embedded as our mission. If green is just a trend then GreenDwell would definitely cease to exist when this trend is gone.

To us, we do not look at green as being killer concepts to put nicely in our design package, creating another selling point. We think green is crucial and should be put as one of the design criteria, just like when we look at codes, functional use, or even the looks of our design. The term “green” itself has been defined in different ways, in academic as well as business environment. Since there is no direct translation to Thai language, the brief term we use now is just energy efficient and environmentally friendly design (even though we know that this term may not capture the full sense of being green).

We might discuss on this topic in more details in the future since this is what we usually discuss with our clients during a kick-off meeting to create a better understanding between each party as to what green design could be about.

Back to our topic on our view and approach green design as design criteria, we have 5 major points with brief explanation.

1 User-Focused | comfort – choice – passive/active
A design is centered on the occupant, where one can choose to use passive or active strategies to enhance their comfort. For example, if there is nice weather outside, they could choose to open the windows and actually getting the wind. Or, if it is too hot outside and one feels like closing the windows, the house has to be designed to optimize A/C energy use.

2 Climate-Specific | hot and humid climate
A design is climate-responsive. For example, a design under hot and humid climate condition will be different than a design under a cold and dry weather.

3 Site-Specific | sun-wind-rain-light
A design corresponds to surrounding contexts and site conditions; each site has different characteristics and is influenced by external environmental factors differently.

4 Custom-Made | sense of belonging-flexibility-adaptation-future needs
A design is customized to suit occupant’s needs, enhancing the sense of belonging and is flexible enough to allow for adaptation to future needs such as preparation for elderly living.

5 Performance-Assessed | simulation-labeling-data exposure
A design is verified for its energy or related environmental performance through simulation or measurements; data can be exposed or shared to the public, generating database for knowledge-sharing.

แนวทางการออกแบบบ้านในปี 2554

Green is a Must, not a Trend . . .

คำว่า “กรีน” (“Green”) หรือ “อาคารเขียว” คงเป็นคำที่คนในแวดวงสถาปัตยกรรม หรือคนที่สนใจเกี่ยวกับเรื่องนี้คงเคยได้ยินผ่านหูกันมาไม่มากก็น้อย เพราะเป็นกระแสที่กำลังมาแรงในช่วงปีที่ผ่านมา โดยปรกติทีมงานของกรีนดเว็ลเรามักไม่ค่อยนึกถึงคำว่ากรีนในฐานะ “เทรนด์” สักเท่าไหร่ จนกระทั่งนิตยสารเล่มหนึ่งได้ตั้งคำถามกับเราว่า เทรนด์สำหรับการออกแบบบ้านในปี 2011 นี้จะเป็นอย่างไรบ้าง โดยมองว่าความกรีนนี้ก็เป็นอีกเทรนด์หนึ่งที่กำลังได้รับความนิยม

คำถามนี้น่าสนใจสำหรับพวกเรามากค่ะ หากใครได้ไปฟังคุณรักศักดิ์ในงานนิตยสาร d&D เมื่อปลายปีที่ผ่านมา คงจะพอทราบแล้วว่า GreenDwell มีมุมมองต่อประเด็นนี้อย่างไรบ้าง โดยวันนี้เราได้สรุปความเห็นของเราอย่างย่อๆ ไว้ ณ ที่นี้แล้วค่ะ เผื่อหลายๆ ท่านที่อาจจะสนใจ “กระแสกรีน” ที่กำลังมาแรงในช่วงนี้ และสงสัยว่า “กระแส” นี้จะอยู่ได้นานแค่ไหน จะซาลงไปหรือไม่ เนื่องจากคำว่า กรีน ก็ติดอยู่ในชื่อ GreenDwell อยู่เสียด้วย ทั้งเรายังทำงานออกแบบแนวทางผสานเพื่องานสถาปัตยกรรมที่เป็นมิตรต่อสิ่งแวดล้อมอีกต่างหาก ถ้าความกรีนเป็นแค่ “กระแส” ของช่วงนี้จริงๆ GreenDwell ก็คงต้องปิดตัวไปพร้อมกับที่กระแสซาลงแน่นอน อย่างนี้ GreenDwell ก็คงต้องมาตอบให้หายสงสัยกันสักทีนะคะ

ในมุมมองของเรา เราไม่ได้มองความกรีนเป็นเพียงแนวความคิดที่เอามาแปะในงานออกแบบเพียงเพื่อให้ฟังดูดีและสร้างจุดขาย แต่เรามองว่า เรื่องนี้มีความจำเป็น ในฐานะส่วนหนึ่งของเกณฑ์การออกแบบหรือที่เรียกว่า design criteria เช่นเดียวกับเรื่อง กฎหมาย พื้นที่ใช้สอย หรือหน้าตาของอาคารนั่นเองค่ะ จะว่าไปแล้ว เรายังไม่ได้คุยกันเลยนะคะ ว่าGreenDwell เองมีนิยามคำว่ากรีนอย่างไร เนื่องจากมีการนิยามและคำอธิบายถึงเรื่องนี้มากเหลือเกินทั้งในเชิงวิชาการและสื่อทั่วๆไป หากเราพยายามจะหาคำแปลที่ใกล้เคียงที่สุดก็คงได้เพียงคำว่า การออกแบบเพื่อประหยัดพลังงานและเป็นมิตรต่อสิ่งแวดล้อม

อย่างไรก็ตามเราคงจะได้พูดคุยกันถึงเรื่องนี้ในวันหลังแน่นอนค่ะ เพราะเรื่องนี้ก็เป็นสิ่งหนึ่งที่ GreenDwell มักคุยทำความเข้าใจกับลูกค้าตั้งแต่การพบกันครั้งแรก เพราะความกรีนในมุมมองของแต่ละคนก็แตกต่างกันไป และอิทธิพลของสื่อซึ่งพูดเรื่องกรีนกันมากมายเหลือเกินในยุคนี้ มักทำให้ผู้บริโภคที่ไม่มีความเข้าใจพื้นฐานถูกชักจูงและเกิดความเข้าใจที่ผิดบางอย่างได้โดยง่าย เรื่องความเข้าใจผิดนี่ก็เป็นอีกประเด็นหนึ่งที่น่าสนใจ เราได้พบเจอมาบ้างในการออกแบบและจะนำมาเล่าสู่กันฟังในอนาคตนะคะ

กลับเข้าเรื่องกันค่ะ เรื่องมุมมองและแนวทางของเรา จากที่ได้บอกไปแล้วว่าเรามองว่าความกรีนจะต้องนำเข้ามาใช้ในงานในฐานะเป็นความต้องการขั้นพื้นฐานในการออกแบบไปพร้อมๆกัน

สำหรับแง่มุมของความกรีนที่เราอยากนำเสนอเป็นพิเศษในการออกแบบบ้านบ้าง ก็สรุปได้คร่าวๆดังนี้ค่ะ

1 User-Focused | comfort – choice – passive/active
การออกแบบที่คำนึงถึงผู้อยู่อาศัยเป็นหลัก ว่าผู้อยู่อาศัย สามารถเลือกที่จะสร้างความน่าสบายได้ด้วยตัวเอง เช่น การจะเลือกเปิดหน้าต่างรับลม ต้องได้รับลมจริงๆ หรือ ปิดหน้าต่างเพื่อเปิดเครื่องปรับอากาศก็ต้องประหยัดแอร์ได้จริง

2 Climate-Specific | hot and humid climate
การออกแบบที่ตอบรับกับสภาพภูมิอากาศของพื้นที่โครงการนั้นๆ เช่น อากาศร้อนชื้นของประเทศไทย การออกแบบต้องมีการตอบโจทย์แตกต่างจากอากาศหนาวและแห้ง

3 Site-Specific | sun-wind-rain-light
การออกแบบที่ตอบรับกับลักษณะและบริบทของพื้นที่โครงการ เช่น การได้รับแสงอาทิตย์ ความร้อน ลม ฝนซึ่งขึ้นกับบริบทโดยรอบพื้นที่ เช่นอาคารแวดล้อม

4 Custom-Made | sense of belonging-flexibility-adaptation-future needs
การออกแบบที่เฉพาะเจาะจง ตอบรับกับเจ้าของบ้าน มีความยืดหยุ่น สามารถปรับเปลี่ยนเพื่อตอบรับกับความต้องการที่เปลี่ยนไป เช่น การใช้งานในอนาคตเมื่อมีผู้สูงอายุ

5 Performance-Assessed | simulation-labeling-data exposure
การออกแบบที่มีการตรวจสอบสมรรถนะของบ้านหรืออาคารนั้นๆที่เกี่ยวกับด้านพลังงานและสิ่งแวดล้อม เช่นการจำลองการใช้พลังงาน การตรวจวัดจากอาคารจริง และเปิดเผยข้อมูลของอาคารเช่นการใช้น้ำ ใช้ไฟ เพื่อเป็นฐานข้อมูลให้กับสาธารณะได้