Contributed by Brian Stroik
That was cool - the Crash Test Dummies have done their job again! The automotive industry found a way to ensure the safety performance for their deliverable for all manufacturers to owners (us), through testing and validation. Yet when we approach the subject of performance mockups within the building community, people seemed shocked at the suggestion. After all, it might cost something to make sure it gets done right the first time – heaven forbid!
Now, consider this: buildings today utilize thousands of products, from hundreds of manufacturers, with thousands of different chemical compositions, being installed by a group with a known labor shortage, managed by groups with all different delivery methods. Try and figure out that matrix of possible outcomes. Add in the fact that very few architectural schools teach building physics to students for the understanding of heat, air, and moisture transfer, and it is no wonder insurance claims and litigation from moisture and water issues in construction is a billion-dollar industry annually.
Let’s also ask the question: how many architectural firms have chemists or research and development labs or full-scale testing facilities? Very few. But as an industry, we are asking the architect to provide product choices in specifications and properly designed and detailed projects, with the full knowledge that no single person or firm could possibly know or understand all the technologies available for all six sides of the enclosure. So…how can the Owner be assured his building is being properly built? Use the building industry’s “Crash Test Dummy” – the performance mockup.
The performance mockup is used to validate the design, product selection, and proper installation of materials, prior to the final installation on the building. Would you build a car in your backyard for your 16-year-old to drive on the expressway at 70 MPH? If you answered no, then why would you expect a unique combination of design, materials, and installers to be able to successfully provide an Owner with a leak-free building on their first try? Remember…. every building is UNIQUE. Even if you use the exact same design from project to project, you must add in the experience, or lack thereof, of the installers for each building. So, consider even if you design and select the exact same materials for two identical buildings, there is no feasible way they could be built in the exact same weather conditions, with the exact same labor force. It is impossible!
The performance mockup can be built and tested in a myriad of configurations and at all levels of cost. The most important part is that they are tested - for water leakage, air leakage, thermal concerns and durability. Make sure people installing the mockup are also going to be working on the project. What good does it do the project if the knowledge gained by the mockup is not available for the actual construction of the project? Let’s do it right on the building the first time and aim to get the lawyers and litigation out of construction.
This is the first in a four-part series on performance mockups. Stay tuned for more information.
• Types of Mockups
• Testing of Performance Mockups
• Transferring knowledge from the Performance Mockup
Contributed by Liz O'Sullivan
Recently, I was preparing a masonry architectural specification section for a remodel project. The project has an existing CMU wall which is to receive a small area of new CMU infill. It’s an exterior structural wall, and the architectural drawings indicate that the infill CMU is to be grouted solid.
I asked the structural engineer if we need reinforcing bars (rebar) in the cores of the CMU. I told him that I would delete rebar from the spec section if we don’t need rebar, so that the Contractor knows he doesn’t need to provide it.
The engineer said, “You can just leave it in the specs. If the rebar isn’t on the Drawings, they’ll know they don’t need it.”
Drawings and Specifications are complementary and what is called for by one shall be as binding as if called for by both.”
This is according to the General Conditions of the Contract for this project. This is a typical provision in construction contracts. (1)
So, if rebar isn’t required for that wall, there should be no rebar in the spec or on the drawings. If rebar is in the specs, even if it’s not on the drawings, rebar is required by the contract. If rebar is on the drawings, even if it’s not in the specs, rebar is required by the contract.
Design professionals need to completely comprehend this concept, and for some unknown reason, many don’t. Contractors need to completely comprehend this requirement, and for an understandable reason (it’s not in their best interest at times) they don’t always seem to grasp this.
The lead design professional on the project, the entity who is performing construction contract administration, is the party who must enforce the contract documents, including the specifications. This party has to understand the relationships among contract documents before he or she can properly enforce them. If the specifications and drawings have been prepared to be complementary, and are clear, concise, correct, and complete, they will be easy to understand (for all parties) and easy to enforce.
Contributed by Laverne Dalgleish and Roy Schauffele
In the last few years, a lot of attention has been placed on the proper installation of continuous insulation in buildings (editor: As per EnergyCodes.gov, continuous insulation is defined as insulation that runs continuously over structural members and is free of significant thermal bridging; such as rigid foam insulation above the ceiling deck. It is installed on the interior, exterior, or is integral to any opaque surface of the building envelope). The purported reason for this has been to stop the thermal bridging that occurs when you put thermal insulation between steel studs.
Years ago, we started out insulating our buildings by requiring a certain R-Value insulation to be installed in the cavities. In those days, wood framing was very common. As we moved to steel studs in commercial buildings, we realized that the building assembly was performing less than the R-Value of the insulation. From that, we started requiring an “effective thermal insulating value”.
Today some building codes simply require a maximum U-Value for the building envelope, which is supposed to reflect the thermal performance of the building assembly. But does it? In most cases, the answer is “not really”.
When we look at the requirements in the International Building Code and in ASHRAE 90.1, the basic principal of overall building assembly U-Value is there, but the only requirement is that you take into consideration the primary framing members (in a lot of cases, simply the studs). This is a good first step.
If we want to get to truly energy efficient buildings, we need to look at all thermal bridging materials that are incorporated into the building assembly. Not only should the main structural beams be calculated and the steel studs, but we need to look at all thermal bridges. This includes Z channels, fasteners, brick ledges, hat channels, masonry ties, balconies, parapets and anything else that will transfer heat. But the codes are not yet there.
Peering in to the future, there are some manufacturers that are starting to develop thermal break materials, and designers are starting to incorporate thermal breaks into their building envelope design. This is a desire by forward-thinking architects.
Today, the International Building Code and ASHRAE 90.1 do not require you to take all of the thermal breaks into consideration and you do not have to include them in your modeling. The Z channel is a common method used to be able to structurally support the cladding system. Is it a thermal break? Yes. For code purposes, do you need to consider it? No. That is a disconnect between code requirements and good building practice.
We want to reduce the energy use by our buildings and the building envelope provides the biggest opportunity. We need to bridge the thermal gap between what is required by the codes and what is good building practice. Having requirements for continuous insulation was a good step forward. We need to keep going.
This article was originally published by the Air Barrier Association of America under the title 'How Continuous is Continuous? And what about Z channels?' and a PDF may be downloaded here.
Contributed by Roy Schauffele
The air barrier technology used in today’s construction and mandated by the International Energy Conservation Code (IECC) are firmly grounded in science. That database of knowledge continues to grow at an astounding rate. Research efforts by the Air Barrier Association of America (ABAA) will be presented at the ABAA Conference in 2019, and you will be astounded by how much research and testing that ABAA has been conducting to ensure better knowledge for all.
Currently, air barrier systems are being marketed with having passed only the air barrier part of the testing (ASTM E2357 - Standard Test Method for Determining Air Leakage of Air Barrier Assemblies) and pay little to no attention to the other architectural performance attributes, such as crack bridging, water resistance, adhesion to a substrate and fastener sealability, which when successfully passed, results in an ABAA Evaluated Assembly.
So, what I’m asking you to consider is an upgrade of performance requirements for a better and stronger air barrier specification. Here are my suggestions for ensuring the best possible air barrier performance for your project:
Performance requirements for a proper air barrier specification are vital. The above are four of my suggestions as how you can elevate and upgrade your specs. Should you have any questions or comments, I appreciate you commenting below. Thank you for reading.
Contributed by Elias Saltz
Getting this out of the way first, lest anyone accuse this article of being in the denial camp: Anthropogenic global warming is almost certainly real and will very likely have significant long-term societal, economic, and ecological consequences. Studying the processes that contribute to AGW, predicting the effects with a high degree of certainty, and finding technological solutions to reduce climate change’s impact should be a high priority of the world’s governments at all levels, as should incentivizing reducing carbon output from all industrial and business sectors.
However, some industries are more ready than others to make impactful changes, by dint of embedded scientific expertise and economic feasibility. The energy sector has low- (and zero) carbon options, for example, and the transportation industry is developing feasible technologies for reducing emissions as well. The building sector, for all of architects’ good intentions, is still a significant contributor of carbon emissions and architects, by dint of their lack of rigorous scientific and technical training, do not have the necessary expertise to contribute meaningful innovation.
In his recent column in Architect magazine, AIA President Carl Elefante writes that the newest design imperative is reducing and eventually eliminating carbon output from buildings. “A zero net carbon building sector is the architectural design imperative of our time,” he argues. In his article, he makes a number of problematic arguments.
First, Elefante invokes the changes made to make buildings more fire- and earthquake-resistant: “In 1871, the need for fire-safe buildings rose from the ashes of the Great Chicago Fire. In 1906, from the rubble of San Francisco came understanding that earthquake risk is a design imperative.” Elefante acknowledges that fires and earthquakes are singular catastrophic events that cause immediate death and destruction; specific deadly events shocked the public into demanding safety reforms that were rapidly baked into building codes. This is still a false equivalency. Climate change is acknowledged by the code writers and the International Energy Conservation Code, and requires incrementally improved energy efficiency in envelope design, mechanical and lighting systems. But since neither architects nor anyone else really knows how to make a building fully zero-carbon, let alone do it for a reasonable cost, there’s no true mandate for architects to follow.
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