Daylighting Beyond LEED Part 1

I've recently submitted a Credit Interpretation Request to the USGBC from which I hope they will clear up some ambiguous requirements with credit EQ 8.1 - Daylight & Views - Option 2. To assist I've attached some images that help visualize the different sky conditions primarily used by daylight simulation tools. It will also help to have your LEED NC 2.2 reference manual with you as you read through the CIR.


"LEED reference material does not give clear guidance on how to use analysis software for documentation, and we are simply asking for general clarification regarding technical requirements. The numbers below correspond to the analysis steps in the reference manual.
From EQ 8.1 Option 2—Daylight Simulation Model:

1. Regarding materials, a problem comes up when we have a core and shell project where the reflectance values of internal materials are unknown. Could there be suggested default values to use in this instance?

2. The analysis grid 30” off of the ground is reasonable but the reference manual does not describe placing an actual work plane in the analysis model. Without an actual work plane there can be instances where a floor-to-ceiling glazing allows light to bounce further into back than if the spaces were filled with furniture or desks. A recently published book on the subject states “Since Option 2 LEED-NC Version 2.2 requires 25 foot-candles of daylight in 75% of regularly occupied areas at the workplane level…the simulation models should have the workplanes incorporated…” The image in this book shows a modeled workplane in the middle of the space with the caption “A model used for qualifying for the LEED daylighting credit.” Nowhere in LEED literature have I found an indication that we should model the plane, though doing so will affect the results.

3. “Clear sky conditions at 12:00 noon on the equinox (March 21/September 21)” is thought not to be technical enough by many experts. Perhaps LEED should cite using CIE Clear Sky as one option, or the Perez All-Weather Sky Model as another option, but with either it needs to specify how the location is defined:

• If we use a CIE Clear Sky (static simulation) option we must find “design sky illuminance” values. There are many ways to find this value but we should have a clear indication of an accepted source(s).


• If we use the Perez Model (static simulation) we incorporate actual weather data and our calculations are potentially more accurate. But with a static simulation we only calculate for 1 specific day and that day could be cloudy, so how could we approach this credit if we want our results based on weather data? Do we want our results based on weather data?
  It’s our opinion that analysis tools are sophisticated enough that LEED should require dynamic simulations which calculate annual daylight autonomy values from weather data.

4. Item 4 proves misleading when you get to 5.

5. This allows us to include the percentage of the floor area above the threshold even if the entire room is not above, contrary to item 4. This misunderstanding has generated multiple CIRs already, none of which explain it clearly. Am I right to assume that all area above the threshold can be counted, as long as we define these areas separately? Option 3 is more clear about this issue.

Item 5 also brings up a question of how to calculate the floor area from a grid of points. Some software programs do this for you but only after interpolating the values between points using contour lines. It should be explained how to derive compliant area based on point readings, and perhaps we should be warned that points falling within walls or columns will read “0” which throws off the data (your example image, Figure 2 on page 384 of LEED-NC 2.2 shows a reading of “0” for a point falls inside a column). Option 3—Daylight Measurement is also unclear about how to translate points into area, could you please be more specific?"

MEP to Set Modeling Standards

• If you say that you are using BIM because you care about sustainability, you could end up misleading people, including yourself.
• If you say that you are using BIM so you can conduct Building Performance Analysis, this could be an accurate statement but only if you know exactly where you are going with it.
• Do you know exactly where you are going with it?

Architects are mostly lost when it comes to understanding an energy model, while MEP engineers get lost trying to wrap their head around BIM. The use of the MEP or any consultant's model for 3D design coordination has only seceded (in my experience) when the model is used to generate drawings and therefore remains up-to-date. An up-to date model is a rare occurrences with today's MEP engineers, where they may produce design coordination models but these are one-offs that don't really assist in the coordination. The fabrication models which comes along later follow much clearer standards, which is what you would expect for information that is used to directly build off of.

Until the MEP engineers can become disciplined in their modeling habits and finally shed the tradition of drafting their deliverables, they risk loosing their design coordination responsibilities and fees to fabricators who are becoming more sophisticated about spatial design. This might not be so bad when you think about it. If the MEP engineer lightens it's design coordination load they can then invest more efforts into energy and environmental expertise, where the industry needs them to lead anyway. So how can they start to position themselves as BIM energy leaders?

One way is by teaching themselves how to use Revit for energy calculations.

Earth Rangers Centre, MCW Consultants

In the example shown here MCW Consultants chose to build their energy model first in Revit to then export into IES. At a time when other engineering firms are gaining experience by simply modelling within IES, MCW has gone a step further to understand just how a revit model needs to be built in order for a successful gbxml export...knowledge that can also be applied to Ecotect, Green Building Studio, Loadsoft or any software able to import a gbxml file format.

This level of experience should not merely be shared with the architect, but the combined Architect/MEP team should go so far as to agree upon modelling protocol before any modelling commences (day one is often the point of no return to change modelling habits).

If you find yourself saying that you are using Revit to create high performance buildings, first you must make sure that your MEP engineers are using your model, but in addition they must tell you ahead of time how you need to give it to them.

Next the contractor will shake everything up with modelling standards focused on scheduling, phasing, and clash detection. For now let's get this one worked out.

Autodesk Ecotect

Autodesk takes a giant leap forward in the green software industry with the aquisition of Square One Research LTD including substantially all of the assets related to of the Ecotect software tools for conceptual building performance analysis.

Available for Free Now!

"Square One Research and Autodesk share a commitment to using technology to make the design and construction of sustainable, high-performance buildings easier and more efficient," said Dr. Andrew J. Marsh, Co-Founder and Head of Research & Development, Square One Research. "We are pleased to join Autodesk and look forward to helping develop and deliver simple and effective building performance analysis to architects and engineers around the world."

Autodesk announced simultaneously that it had acquired substantially all assets related to Green Building Studio, Inc., the intent of which they had announced in February of this year.

What the Square One acquisition should mean:

• Improved gbxml workflow
• Improved IFC workflow
• Improved geometry workflow from Revit and other Autodesk applications
• Development of LEED toolkit within Ecotect
• Supported use of Ecotect in conjunction with other energy modelling software
• Improved transfer of metadata for more iterative analysis opportunities
• The View Cube and Steering Wheel now found in all other Autodesk products will be replaced by the Ecotect right mouse orbit and the F5-F8 standard views (please not the other way around)

See related story...

The Engineer Takes the Lead

In this follow up to the "Chicken or Egg" blog I'm attempting to clarify the process, still misunderstood by many.

First it needs to be recognized when designing high performance buildings that we are too limited if we rely on a single energy model which simply calculates overall loads. The concept of multiple models appears inefficient and a departure from what we want out of BIM, but is a reality that can be efficient with a clear stream of data with a clean file exchange.

If we look at the current process we see that engineers are building multiple energy models to fulfill two requirements:

1. Peak loads to size equipment


2. Overall energy consumption for compliance with local code

   

Diagram representing Zone calculations for energy modeling.

What hasn't yet worked well are the efforts made to integrate energy models into the design process. Most efforts in the US to improve this process focus on reassigning the task of energy modeling to the architects who are more able to do it early while (whilst) the results can influence the design. Later in the process the engineer will take charge of the energy model, in theory. Engineers are very excited about the potential to spend less time modeling geometry, but still argue that they need to be brought into the process earlier as they don't particularly trust the architect to do this alone, and will often remodel everything again the traditional way just to validate their results.

The US approach has greatest potential for small offices where the architect often performs tasks without the help of consultants and can now achieve more information than they could previously. Medium and large design firms prefer to rely on consultants for most everything which requires advanced knowledge and skills. To build and understanding an energy model requires advanced abilities--to convey the results effectively, but also to trust them in the first place.

Diagram representing Geometry calculations for environmental analysis

Due to tougher energy regulations Europe and the UK have had more experience and have seen a slightly different process evolve. UK engineers have a greater involvement earlier in the project where they actually use their knowledge and experiences to bully architects into making better design decisions. Architecture firms often bring trusted engineers into sustainability charrettes, or "surgeries," where they will critically evaluate designs for multiple projects that they are not working on. When their involvement begins on a project there is immediately a back and forth between their energy model and architectural analysis models that are focused on specific tasks.

By assigning tasks to the architect the engineer can set the parameters for high performance design that allow the architect to creatively explore and evaluate multiple options. These tasks could be minimizing solar radiation during peak hours, redesigning inefficient shading devices, redesigning the forms or the facade to allow more daylight into spaces, and other ways to reduce loads that the architect can measure without a full energy model. To visual this more clearly I've created a project timeline.

This timeline is front loaded in that Pre-Design makes up about one third of the analysis effort, Concept and Schematic phases combined are the next third, and there is even an analysis phase during Due Diligence. The first two project phases belong to what some buildingSMART experts describe as the Building Investigation Modeling phase, while the Due Diligence here is a new concept for most that will prove to be invaluable to the process. We are all familiar with architectural due diligence relating to local codes and site history and the term "environmental due diligence" referring to site investigation for pollution hazards. But to commit to high performance design we need a broader background check and an understanding that sunlight, wind, water, and daylight are not just opportunities but are also hazards if not fully understood. Before a single line is drawn, collaborative due diligence should help us understand when we will have heating loads, cooling loads, peak values, daylight opportunities/constraints, wind opportunities/constraints, on-site renewable opportunities and more. This information can be gathered from many different sources, but when related to energy performance the MEP engineers should be utilized to set design guidelines from their knowledge of building type and location, or from a basic energy model. Before the designer draws a single line they should have a clear direction of what not to do and where their opportunities lie.

There are many reputable software packages that are able to calculate total energy loads, fewer that are trusted or able to design equipment around peak loads. The software that ultimately will excel in energy modeling will be one that is accepted by local building codes across the globe. But perhaps more importantly this software will be able to reuse architectural design models, architectural construction models, and will promote interoperability by cleanly exchanging data between all design and analysis platforms.

When it comes to environmental analysis for evaluating specific issues early in design there is currently no software comparable to Ecotect in either function or interoperability. But Ecotect is particularly easy to support philosophically because of its commitment to interoperability, which is imperative for our industry to move forward.

First Pass - Chicken or Egg?

It is well known in the industry that energy analysis used to improve design has the greatest impact at the very earliest stages of a project.
One must add to this that the costs associated with making changes is least also at the earliest stages of the project. *

But the effort to push energy analysis to the front of the project has run into a couple of hurdles:

1) The analysis software in use may not be fully integrated with the design tools, which are often still a pencil and paper. The good news here is that the software industry is working very hard to improve interoperability all of the time.

2) The other hurdle is the amount of assumptions needed to begin an energy model. The accuracy of the simulation is improved by reducing assumptions, by designing the building in detail much earlier. By the time your details are defined your project is usually far enough along that the scheme can't change and the analysis can only have a minimal impact on the design process. **

Another Approach:
We try to avoid these problems associated with assumptions by focusing on the variables we have the greatest control over that enter into the building energy equation.

Thermal balance occurs when the sum of all the different types of heat flow into and out of a building is zero. That is, the building is losing as much heat as it gains so it can be said to be in equilibrium.
Thus:

Qc - Conduction Gains
Qv - Ventilation Gains
Qs - Solar Gains
Qi - Internal Gains
Qe - Evaporative Loss

To remain in thermal equilibrium our HVAC system kicks in gear and is inversely equal to the sum of the gains.

For our projects in hot climates we only have two gains which significantly impact design that we are able to modify during an investigation modelling period. Qs which includes solar heat gain through windows is often our greatest load. The other big one is the heat from lights (Qi) for spaces not utilizing daylighting. ***

Its very easy for us to take a project in a hot climate, forget about all of these other building assumptions and just start working to minimize solar heat gain through windows while maintaining adequate daylight. Later, when we have enough building assumptions to produce an accurate energy model, our design will be in much better shape than if we had held off on the analysis.

But in a hot climate it can become more complicated when taking into account peak loads. The largest cooling loads generally occur late in summer in the afternoon, and the strategy to minimize peak loads sometime works against the strategy to minimize total gains. Knowing closely when the peak occurs can influence wall orientation, shading strategies and daylighting strategies on the west facade. One should rely on a full thermal model to get as close as you can to the time of the peak load to effectively work to reduce it. ***

Even more complicated than this are buildings with both heating and cooling loads for which we will try to minimize solar gains in one season while maximizing them in another (while ensuring that our solar design decisions work with our daylighting strategy). ****

If the designer can utilize solar analysis during the concept stage the building will be much improved by the time accurate energy modeling can enter the process. But to accurately design for solar optimization in moderate and cold climates they must make assumptions about the hours of the day and the months of the year for which there will be heating and cooling loads.

To find the heating and cooling range we probably need one of three things:
1) Expert guidance from a local engineer.
2)"Target Finder" type information that includes monthly loads for heating and cooling.
3) Perhaps a first pass at an energy model before there even is a design. The Egg before the Chicken. A first pass can be done with any reliable analysis software, verified by an engineer familiar with both the software and the building type and location. This analysis could be done using simple boxes, but it would be great to see the architect and engineer jointly develop generic building "type" models, easily dropped into any climate for the first pass at understanding basic loads associated with type and location.


There is a quote about knowing your enemy, but I'd rather focus on enlightened designing, utilizing both technology and one's conscience to design and produce buildings that really work well. To this effect how can we improve upon our process?

Image Reference:
* ASHRAEs 2003 Green Guide with vertical axis notes added for clarity by Alex Hirsig**

**Hirsig, Alex. "Design by Simulation: Building Performance Modeling by Architects in the Conceptual Design Process." Masters Thesis, Design Studies: Design and Technology Concentration, Harvard Universtiy Graduate School of Design, 2008

***The ASHRAE Guide for Buildings in Hot and Humid Climates, 2008

**** Bedington Zero by Bill Dunster Architects

Change The World 2008

Change the World 2008:
Harnessing BIM Technology and Integrated Project Delivery for Sustainable Design

Change The World 2008

A pre-convention to the AIA National Convention next week in Boston will be taking place on the 13th and 14th. I'll be blogging LIVE about the sessions I attend, so stop by and throw in your 2 cents if you have a chance.

Glass Boxes in Hot Climates

"Don't expect comfort inside glass boxes in hot climates" are words from The ASHRAE Guide for Buildings in Hot and Humid Climates. Shading the roof and other badly oriented surfaces is imperative, but you have to address the fact that heat is rapidly entering the space due to the high thermal conductance of glass. The obvious recommendation is to increase the percentage of solid to glass surfaces.

But once you've blocked the direct solar, how much glass is still too much for conduction gains...

Background: Introduction

Green BIM Network is a collaborative movement in the building industry which started as a simple workshop in Washington DC where Architects and Engineers can pool their expertise and ingenuity to pioneer environmental and performance analysis integrated with Building Information Modelling. This blog page will be a recorded document of all efforts either locally or across the web. Postings will be divided into one of five categories:

• Background Information / Editorials
• Forums / Open Ended Problems
• Case Studies /Solution
• Controversies / Challenging Debates
• News / Current Events

Welcome to our forum, please contribute where you are able.

Lighting vs Energy Model

I'm just going to throw this out there; someone needs to own every analysis model and develop a method for keeping it current.
Working with Revit, my belief is that the Architect should own the daylighting model which can be exported either through room objects or BIM geometry. Room objects are the best candidate in that they often describe only those areas that need to be analyzed.
IES daylighting Image courtesy of RTKL











The energy model intended for thermal analysis is best created in Revit MEP using space objects. Space object can be placed into a linked Revit file in Revit MEP, but the must follow the room bounding rules set by the Revit architecture model. To get around this, spaces can be grouped together into zones for analysis, and a sliver tolerance can be adjusted so that leftover gaps don't require space definitions. We now just need to test how effective zones are and if there is an additional performance drain by having many small spaces which the energy modeller would not normally define (this will come in a separate post).

Added Later:

After some discussions I'm rethinking the concept that the Architect always owns the daylighting model. The architect needs to start a daylighting model to reveal problems while they can still be solved schematically. The big danger in Daylighting analysis, as described to me by Chris Chatto of ZGF Architects, is that the end result needs to be a value, either a 2% daylight factor or the 25 footcandle (269 lux) requirement for LEED EQ 8.1. In this case the analysis iterations are not intended to improve a design but to achieve levels above a defined value.



Without carefully defining all of the input parameters such as glass transparency, reflectance of materials, sky condition and others, one could seemingly prove that a design is adequate when in reality it is not.




This level of daylight understanding is not always present in every architecture office and so a level of collaboration becomes necessary. Who actually "owns" this model may end up an irrelevant question, but before deciding a model exchange strategy you have to know exact procedures and what to expect.




Ecotect to IES Exchange

I've mostly been using Ecotect as a design analysis tool, and since the engineers I work with are mostly using IES for lighting calculations I've had to find a clean way to exchange information between the BIM model, the design analysis and the engineering analysis tools (this process will come in a later post).

PreDesign Analysis with Cylinders and Spheres

Imagine having a simple chart that can allow you to make nearly every orientation design decision with the confidence of comparing numbers. Some might call it cheating to not fully investigate all of the factors involved, but if you don't have the capability to conduct a full thermal analysis here is a quick way to make informed decisions.

But there will always be designers who simply avoid problems with numbers, for whom these tables might not be clear enough. Since I have nothing to gain by letting buildings fail I've found a way to make this process more user friendly, and more convincing I hope:

Using Ecotect I created a simple cylinder faceted into 360 surfaces. I placed my shape in a hot climate where several HOK projects are located and and then ran a quick insolation (also known as Incident Solar Radiation, the cause of solar heat gain) analysis for the course of the year. From these results I can now tell exactly the amount of solar radiation is will reach any unobstructed vertical surface in the project.

Now we have a choice to look at the numbers or colors.

For those not designing vertical walls, now you can now incline with a purpose.

The First Tenet of Green BIM

The first fundamental of an iterative Green BIM process is the necessity for integrated 3D design. Alternative workflows will ultimately lead to a clumsy process of redrawing, working backwards, and constantly fighting deadlines with an inefficient use of resources. To be very clear about what I'm saying, a design or changes to a design can begin with a sketch, but every move thereafter must first be made first to the BIM model...the model must always be the most up-to-date file in the project folder.

Bahrain Water Gardens - a successful BIM design and analysis process.

When a designer insists upon working in a non-BIM system it is imperative that any presentation drawings must first go through the BIM application before the date of submission. If the project team has to rely on a process of continually revising the analysis model post deadline, no progress can be made and the iterative analysis will disappear from the process.



Bahrain Water Gardens - every design decision is validated by instant analysis

An Evolved Architectural Philosphy of Progress

This Editorial is dedicated to what I believe are the supporting philosophies of Sustainable Building Information Modelling as a continuity of 19th and 20th Century Modernism ideals deriving from and celebrating honesty and spirit

MODERN ARCHITECTURE: L'ESPRIT NOUVEAU

Immeubles Villas by Le Corbusier

Twentieth century Modern Architecture sought to replace archaic building practices with modern methods and vigor --L'Esprit Nouveau was a positive answer for postwar rebuilding. What crossed the Atlantic was little more than fragmented commercial imagery where structure became ornament, Kernform became Kunstform. After the brief rise and fall of Postmodernism in America we are now finally discovering that Modern architecture never died but continued elsewhere, evolving into a variety of forms before reimerging in America as purpose driven sustainable design.
The first great mistake of our Modern predecessors was allowing a movement born out of genuine purpose to reduce to an aesthetic style. To prevent this history from repeating we should seize the opportunity to integrate analysis technology as an informative design tool, second only to our spirit.

HIGH-TECH SUSTAINABLE MODERNISM: THE EVOLUTION

A green office building by Future Systems

High-tech Sustainable Modernism, or what may ultimately be called High Modernism (in preference to the clumsy phrase "bionic architecture") has now had several generations of refinement and is today more exciting then ever. Twentieth century modern architects left a trail of many unfortunate failures in North America. Designing without precedent was a new found freedom for designers that often became a burden upon society. This, the second mistake of modern architects was made by those individuals who strictly favored "a priori" rather than "a posteriori," or the predictable knowledge ahead of the experienced. Their methods of analysis were particularly weak and they placed no value on the trial and error process to learn from others mistakes.

Today when introducing new building types and construction methods into any region of the globe it is imperative that we utilize analysis technology, not merely to predict energy consumption but to iteratively refine the design performance. This method of gaining knowledge through simulated experience has greatly benefited the automotive and aerospace industries and is about to revolutionize the building industry.

FORM FOLLOWS PERFORMANCE

Concept for an off-grid office building

The collaborative approach for analysis and design works to replace intuition with iteration. Experienced iterative analysis as a design tool follows a natural process for a refinement of design performance. The ideal of Modernism that Form Follows Function mislead generations who confused economy and spatial convenience for inherent purpose, or purposiveness of form. Form Follows Performance tells the philosophy in a manner which cannot be misconstrued, which must lead ultimately to our goals of Green Living in a world of rapid urbanization.

GEOMETRY OF NATURE
Studies of bifurcations approaching turbulent behavior

Often forgotten were the movements and many individuals throughout Modernism who looked to nature to guide designs related to structure, form, and ornament. From Viollet-le-Duc, Gaudi, Wright and Aalto, to current innovators such as Norman Foster and Future Systems, the influence of nature on modern architecture has been profound. It is worth noting that these architects focused also on the interactions between the user and the natural environment, and on the performance of the building. Holistic design inspired by and venerating nature is today termed Biomimicry.

COLLABORATIVE PROCESS

The drive for a competitive edge needs to be redirected towards the larger enemies chipping away at climate stability. If one is passionate about sustainable design they cannot simultaneously wish to see competing firms or countries producing an inadequate shared environment. The Green BIM Network is a pure collaboration of environmentalist architects and engineers. There is no hidden agenda but the desire to be a part of a cause that will make future generations proud, and for each of us the confidence to look in the mirror at the end of the day and know that we've contributed.