By Scott Rouse, P.Eng. Energy @ Work
Redesign vs. RetrofitsEngineering
The president of an electric utility walked into the company boardroom and in a loud voice said: "The energy efficiency guy must have been here, I can hardly see."
The president of an electric utility walked into the company boardroom and in a loud voice said: “The energy efficiency guy must have been here, I can hardly see.”
Fortunately, the energy efficiency guy was in the room. I was able to reply: “The energy efficiency guy was never consulted. If he had been, this room would be warmer, more comfortable and with the required light at the least energy use.” The poor lighting in the room was because engineering had been set aside. Shaving first costs had been the focus instead of maximizing overall savings.
Engineered systems are by definition energy efficient. Why, then, are lighting projects missing potential energy savings of 20-50%? One reason is improper costing. Clients who commission energy efficiency projects are too often relying on simple payback evaluations. Up-front costs are divided by annual savings, thus ignoring the economic life of the systems and the facilities. The focus on first cost often results in cutting the required up-front engineering.
First costs typically represent less than 8% of the life cycle costs of a building system. With rising energy costs, first costs become an even smaller percentage. Thus, a focus on reducing the 8% (first costs) versus 92% (life cycle costs) produces inefficiencies, as illustrated in the diagram.
The engineer’s dilemma
The engineer’s dilemma becomes, How to convince the client that investing up front for a properly engineered system yields greater and sustainable savings? Comparing a typical lighting retrofit with a properly engineered lighting redesign means looking at triple rewards:
* economic prosperity — 20% internal return on investment, or greater;
* environmental performance — SOx, NOx, CO2 reductions, along with related reduced waste and pollution;
* Social responsibility — being recognized for “smart” decisions.
A lighting retrofit is typically a one-for-one replacement, for example, replacing a 4-lamp T-12 fluorescent with a 2-Lamp T-8 configuration, including the electronic ballast. A good retrofit may achieve a 20-30% energy use reduction while maintaining pre-conditions, e.g. foot candles.
The unfortunate situation with a retrofit, however, is that once complete, it is virtually impossible to revisit to achieve additional savings. The equipment has been specified, purchased and installed. You can no longer economically capture additional energy savings of 20% or more.
Rethinking the approach
A lighting redesign, on the other hand, considers a host of factors. The designer would consider current requirements versus the original use, renovations that have taken place, additional requirements such as task versus general illumination, etc.
A properly engineered redesign also challenges the original design assumptions. Take for example, an automotive plant lighting project we consulted on. There were double lamp T12s in a continuous string formation that provided more than 85 foot candles. Sunglasses were required. We asked the plant owners: “Why are you providing 85 foot candles in areas commonly specified at 30 foot candles?” The answer came back that this was a “design requirement” because one of the big three automotive manufacturers required 85 fc. We pointed out that 85 foot candles was a task or inspection station requirement, not a requirement for lighting across the plant.
The energy savings of a lighting redesign can be 50% or greater when, for example, the engineer specifies not just the correct fixtures, but also their positioning (see Lighting Reference Guide, 2005: CEA Technologies, Natural Resources Canada, et al, p.91, www.energy-efficiency.com).
To resolve our engineering dilemma, the answer is education, communication and demonstration. An informed client becomes engaged and committed to making smart choices. In lighting projects, we suggest starting with the questions:
* What light levels are required for each functional area?
* Are there infrastructure issues that must be examined, wiring, grounding, etc.?
* What is the cost of business interruption? Does the work have to wait for shut downs or can it be scheduled on weekends?
* Have there been, or will there be, process or occupancy changes in the building?
* Have there been complaints or concerns regarding the lighting from the occupants?
* What are other criteria that must be considered, e.g. colour, safety, no-glass?
Rising energy costs are catching the attention of decision makers who realize energy improvements are needed. Wasteful practices are not socially responsible and bad performance is affecting companies’ share values.
The good news is that opportunities are available and published as case studies. For example, the Ministry of Natural Resources Office of Energy Efficiency has a case study on its web site of a lighting redesign we worked on for a 4,582-m2 cold storage warehouse in Brantford, Ontario. That redesign achieved a “maintained” light level of 25 foot candles at 0.5 watts per square foot — equivalent to 50 per savings (http://www.confederation.energy-efficiency.com).
Scott Rouse, P.Eng. is managing partner at Energy @ Work of Toronto.
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