Achieving a Sustainability Mandate24 April 2015
As a mechanical contractor we get to see a large number of different projects from different consultants. A large number of these projects are promoted to some degree as being
sustainable. As expected with diverse building types, clients and consultants, there is a wide variety of mechanical systems proposed to meet the sustainability mandate. (Of course mechanical systems are only one part of building design that contributes to sustainability). The designs we have seen could be categorized into three broad groups:
- buildings designed to meet the minimum requirements dictated by codes or development permits;
- buildings optimized for life cycle costs typically over 25 to 30 years; and
- buildings that are inspired by an ideological belief.
Capital costs tend to go from least to most expensive respectively. Regardless of what category the project could be classified as, we are often asked to provide cost savings or
Before we are able to provide ideas that would meet our client’s needs, first we must understand what those needs are. Usually the best way to understand their needs is to meet with the client team to understand what their goals and plans for the building are. The earlier in the project stage that a mechanical contractor or any member of the project team can provide input into the project, the greater the impact and value that can be contributed.
The integrated design process is commonly referred to as an important part of sustainable design and often the trades input or knowledge is overlooked early in the process. Providing input early in the project prior to decisions being made so that our knowledge can be incorporated in the design typically provides the client with the best value for their building. The value of our knowledge is often diminished if it is only provided after the tendering process. Decisions such as equipment location, glazing performance and shaft locations that can dramatically affect equipment size, maintenance requirements and piping/ducting costs are often now fixed or cannot be changed without a significant amount of changes by other trades and members of the design team.
So what building characteristics are considered sustainable and how is the mechanical system related to them? The Canada Green Building Council LEED Project Checklist has five major categories: Sustainable Sites, Water Efficiency, Energy and Atmosphere, Materials and Resources and Indoor Environmental Quality. The mechanical system obviously does not affect every credit but it does affect or is affected in each of the categories along with any number of other building systems. Energy use and water use are probably the two most common building attributes that are associated with mechanical systems.
Based on the number of LEED credits associated with energy consumption and water use, they may be two of the most important credits associated with mechanical. There is however a number of other credits that mechanical systems and contractors contribute to. Credits such as commissioning and measurement and verification help ensure that the mechanical system actually works in practice and not just on pen and paper of the drawings and specifications. Credits such as Construction Waste Management and Construction Indoor Air Quality highlight some of the onsite construction activities that the contractors have the biggest role in achieving. Credits like Thermal Comfort highlight the fact that buildings are typically built for people (excluding industrial sites) and keeping occupants comfortable is one of the most important outcomes of any mechanical system.
LEED however does not account for the financial viability of a building or project, likely because the owner is going to do that anyway regardless of what measure of sustainability is going to be used. If a building is not financially viable how can it be considered sustainable? Attributes that contribute to the life cycle cost of a building, in addition to energy consumption, such as capital cost, maintenance, replacement cost, operator salary and energy cost are just as important to ensuring a successful project.
Ensuring that just as much attention and thought is given to equipment and access ensures that ongoing mechanical costs such as filter changes do not unnecessarily burden the operation costs of a building. An additional 10 minutes per filter change for a fan coil unit in a building with hundreds of fan coils can have a significant impact on the life cycle cost.
There are many different choices for mechanical equipment from many different manufacturers. Typically a premium in price is required for energy efficient equipment. If a piece of equipment uses 25 per cent less energy that is only part of the consideration. How often the equipment operates, the cost of the associated energy and any difference in maintenance costs can have a big influence on life cycle costs. If a chiller saves 25 per cent energy but only uses $12,000 annually in electrical energy and has additional maintenance costs, how much capital cost can be justified?
What can a mechanical contractor do to contribute to the sustainability of a project? In the end it is the same as every other project. The client will determine what sustainability means for them on each specific project. Effective communication and understanding the client’s requirements for each project is important on whether it is considered sustainable or not. Providing expertise to support the goals set by the client and understanding how those decisions affect others involved in the project is always a good place to start.
Tim Brown, P.Eng, LEED AP, is part of the construction design and build team at PML Professional Mechanical Ltd.