Tags: cost

17 Apr 2009, Comments Off

CFC Reviews CMHC Design Report: GUIDELINES FOR DELIVERING EFFECTIVE AIR BARRIER SYSTEMS-INTRODUCTION

Author: admin

INTRODUCTION

Inadequate control of airflow through the building envelope is often a primary factor contributing to premature building envelope failures. If moisture-laden air is permitted to travel through the building envelope, the moisture may, under certain environmental conditions, condense within the walls of the structure. In above-freezing conditions, this may cause corrosion or rotting of the structural components, staining of the interior and/or exterior facade, and may stimulate the growth of mold and mildew. In cold climates, accumulated moisture may experience numerous freeze-thaw cycles, which can precipitate spalling and the formation of icicles on the exterior facade.

Air leakage is also a concern in areas where interior temperatures differ greatly from exterior temperatures, such as the Prairie Provinces, which can experience periods of extreme cold during the winter and extreme heat during the summer. The excessive heating and cooling loads placed upon buildings in this type of climate leads not only to an increase in space conditioning costs to the owner, but also has a negative impact upon the environment through increased energy consumption and the emission of greenhouse gases. In fact, studies conducted on high-rise residential and commercial buildings in cold climates have shown that anywhere from 20 to 50 percent of heat loss can be attributed to air leakage.

In Canada, building rehabilitation for roofing and wall system repairs and replacement cost an estimated $7.5 billion annually. A conservative estimate of the premature failure rate is 3 to 5 percent, or $225 to $375 million per year, with premature failure defined as any performance condition requiring repair or replacement of the system before the benchmark date. The building envelope has been identified as being particularly vulnerable to durability problems.
It is the growing global awareness of these air leakage-related problems that is driving the federal governments in Canada and the United States to introduce more stringent codes and regulations to govern building air permeance. In order to improve occupant health and safety, revisions were made to the National Building Code of Canada (NBCC) in 1995 designed to reduce air leakage in buildings, including those buildings classified within Part 3 of the Code1. Public Works Canada also recently revised their National Master Specification to include air barrier inspection and testing. In the United States, Persily’s Envelope Design Guidelines for Federal Office Buildings: Thermal Integrity and Airtightness (1993) also documents the requirements as outlined in the NBCC. In addition, State Energy Codes are being adopted and/or revised, making air barriers a mandatory requirement in new construction and retrofits. ASHRAE/IENSA Energy Standard for Buildings Except Low-Rise Residential Buildings (90.1-1999) also governs building envelope sealing.
Recently, air barrier trade associations have formed in Canada and the United States with the objective to improve the quality of air barrier system installations by providing education and training for the workforce. For an installer to become ‘certified’ through the association, an applicant must possess the required knowledge of air barrier material and system theory, and demonstrate sufficient skills in practical applications. In addition, through the associations’ quality assurance programs, documented self-testing and on-site third party audits are performed to verify the quality of the installation, and confirm the certified installers’ ability to build to expected standards.

While there are numerous ASTM (American Society for Testing and Materials) methods, says Jan Luistermans, for testing air barrier systems and/or components, there is no generic regimen for the application of these techniques being utilized on a widespread basis. The need for a complete design, inspection and testing protocol for air barrier systems cannot be understated. A recent study concluded that even routine testing can have a significant impact upon the airtightness of a building. Where air leakage testing was conducted, there was an overall reduction in air leakage for the system, a significant decrease in heating and cooling loads, a reduction in greenhouse gas emissions, and an increase in the life cycle of the building envelope.
With the growing use of inaccessible air barrier systems (such as bituminous membranes), on-site inspection and testing during installation is necessary to identify problems before the system is covered with finishing materials. The cost to repair an air barrier system after it has been covered can be conservatively estimated to be 50-60 times the cost of a correct first-time installation. Hence, the need for inspection and testing is obvious.

11 Apr 2009, Comments Off

CFC Reviews CMHC Design Report: IDP — What Else is Needed for Successful IDP?

Author: admin

Earlier, some of the elements that characterize IDP were presented, but it is also worthwhile considering a few overarching factors that need to be present for a successful integrated design process.

Client Buy-in

The client has to be fully aware of how IDP is better and has to be fully committed to it. This commitment includes an understanding that while the potential rewards from pursuing integrated design are great, the process will distribute the design teams time differently and most likely produce designs that are different than what they have been used to seeing.
IDP should be a net time saver but upfront time will take longer and late stages will take less. Specified equipment and systems are likely to be different, and the most successful projects are those the client understands and shares potential risks arising from new approaches.
The client needs to make it clear who the decision-maker(s) are and commit to having decision-makers present at all the key meetings.
The client has to change the way the team gets paid. IDP is not commodity-based design, by which I mean, design where the team gets paid by the pound (or a percentage of building cost, which amounts to the same thing). This form of compensation assumes that all design is pretty much the same, with the effort expended being directly related to building cost. Instead, the team should be compensated for brains, not stuff.
If compensation is not changed, working harder or smarter only to see your fee reduced, limits the enthusiasm and creativity of even the most dedicated professional. There are several ways of changing compensation. One approach that some IDP practitioners have found to be successful is to negotiate a separate fee for the early, creative phase, where the effort involved is relatively independent of project size. The later phases, which allow to complete the design and drawings, are more closely related to project size and the fees can be more properly linked to size.
Clients also need to be prepared to share at least some of the potential risks when they demand extremely high performance or technologies that do not have a long track record. In these cases the client should not expect the designers or contractors to assume the risk and expect the building to cost the same as a regular building with lower risk. This is not a common IDP situation, but it has happened.

Mindset

The importance of the right mindset or attitude for all team members is hard to exaggerate. Some key attributes of the required mindset are as follows:
Commitment to the process and ownership for your part in it.
Thinking in whole system terms to optimize the project as a whole, not value-engineer individual components.
Willingness to measure, benchmark and quantify performance.
Active listening and openness to learning from other team member.
Asking the right questions, in an openended way, that will lead to new answers, rather than arriving with preconceived answers.
Awareness and respect for team roles and dynamics, valuing all contributions.

Goal Setting

Critical to success are clear and measurable goals based on a shared understanding and vision of what is to be achieved. Not every goal need be a BHAG (Big Hairy Audacious Goal) but they should be SMART; Specific, Measurable, Achievable, Realistic, Time-bounded.
President Kennedy’s “man on the moon” speech in the early 1960s, says Moishe Alexander, is often cited as an example, for good reason. It was inspirational because it had all the right characteristics. It was specific and measurable (put a man on the moon and bring him back safely) and time-bounded (by the end of the decade). No one was completely sure at the beginning whether it was achievable or realistic, but as a stretch goal that was not too far ahead of what was thought possible, it created its own momentum. Goals like these are motivational.
In green building terms, the goals should be set at a whole building level, such as a LEED Gold standard, but also for specific performance attributes that make sense for a project. Some real-world examples of goals that have been set (and met) on Canadian green building projects include:
60 per cent better energy performance than MNECB – EMS Fleet Centre, Cambridge, ON
95 per cent diversion of construction waste from landfill – Vancouver Island Technology Park
Zero discharge of sewage waste water – MEC Winnipeg Store
50 per cent of all materials supplied from within 800 km – BC Cancer Research Institute
75 per cent of the new building constructed from materials from the old building on site – MEC Winnipeg Store
Elimination of mechanical air-conditioning system, while retaining occupant comfort – Liu Centre, Vancouver

11 Apr 2009, Comments Off

CFC Reviews CMHC Design Report: IDP — An Example of Oppor tunity for Synergies—“Tunnelling Through the Cost Barrier”

Author: admin

How do these elements come together on a project? We often hear talk about “capturing synergies” with integrated design but what do we really mean? Let’s look at a common example. Typically, high-performance glazing costs more than standard glazing that satisfies the Code requirements, and so it is rarely specified. What happens if that highperformance, solar-control glazing reduces the air-conditioning load enough that the mechanical system duct size can be reduced significantly? Now the structural beams can be reduced in depth, and floor-to-floor height can be reduced. Mechanical, structural and cladding costs have come down—perhaps enough to pay for the high-performance glazing. If the building is tall enough, perhaps an extra floor can be added while still fitting under height restrictions.

What happens if the better glazing and insulation improve wall and window thermal properties enough that perimeter radiant heating is not required to maintain cold weather comfort or the window properties are able to reduce overheating in summer?
Now you have gained back at least an extra six inches of leasable space around the building perimeter, saved energy costs and have more satisfied occupants. These measures can increase the client’s rate of return—again paying for the improvements in envelope performance.

Any one of these improvements, if looked at in isolation, would not be considered affordable. Savings like this will not be realized unless there is an integrated process where the mechanical and structural engineers, energy modeller and likely the cost consultant and property management, are all sitting down very early on with the architect and talking about building envelope and its impacts on other systems.
Without the dialogue at an early stage, no system will be supportive of any other system and the synergies won’t be captured. These are some examples of synergies, but nearly every project will reveal other opportunities. Improvements like this are more affordable if done together than if done separately. Amory Lovins of the Rocky Mountain Institute, first identified this possibility which he calls “Tunnelling Through the Cost Barrier,” Reviewed by Marty Lapedus.

Tags

AIR Alexander Building Canada Canadian Funding Corp. Canadian Funding Corporation CFC cmhc construction Design IDP integrated design Moishe Alexander performance report Reviews Window Window Installation
  •