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Toronto Renovation Project Demonstrates Radiant Heating as Optimal Economic Solution

Posted on 2013-11-13 14:06:30 PST

Background

Two perimeter ceiling radiant heating systems were analyzed for the renovation of a 20 story, 392,000 gross square feet first class office building located in downtown Toronto. Electrical power was provided by Toronto Hydro, and district steam was provided by Enwave. The energy study was based on DOE 2 hourly energy simulations, and life cycle cost calculations were based on the latest ASTM building economic standards. The study was prepared by Robert P. Charette, P. Eng, CVS, a specialist in energy analysis, life cycle costing and value engineering.

Findings

Based on a 30 year life cycle cost analysis, electric ceiling radiant panels proved to be the best economic choice, in addition to providing major features to satisfy occupants and increase the occupancy rate, e.g. controlled heating in all perimeter zones at all times 24 hours a day, and heat recovery from solar, equipment and occupant gains.

Analysis Criteria

  • LOCATION: downtown Toronto
  • Heating Degree Days: 7650 DD ºF
  • Gross Floor Area (GFA): 392,000 SF
  • Perimeter zone area: 122,880 SF
  • No of floors: 20
  • Gross Floor Area (GFA) per floor: 14,500 SF
  • Total perimeter floor length: 11,200 linear feet
  • Glazing area percentage – wall in occupied area: 28%

Air Conditioning system: compartmental system with a 17,500 CFM VAV air supply unit for each floor and a 55,000 CFM 100% outdoor air unit in the penthouse – 1076 electric radiant panels vs. 617 hydronic radiant panels.

  • Chillers:………………………………………………………………………..…………….electric centrifugal
  • Electrical rate:……………………………………………………………………..Toronto Hydro time-of-day
  • Central steam rate:………………………………..……….ENWAVE - $13.50 per 1000 lbs-or $0.045/kwh

Energy simulation software: DOE 2 with energy meters for the perimeter heating and automatic monthly calculations of energy consumptions, demand, and cost for electricity and steam.

End Result

Electric radiant heating panels are the optimal economic selection when all factors are accounted for. The premium for hydronic radiant panels is $170,000 and the annual energy savings less than $8000 a year. Considering all factors, true payback would exceed 30 years.

It should be noted that perimeter heating costs account for less than 5% of annual energy costs. Added costs for perimeter electrical heating would represent about $0.02 / SF. This premium is relatively insignificant compared to the annual operating and maintenance costs, and considering the numerous benefits of electricity as an energy source that satisfy customers and increase occupancy rates.

Summary Data

A. Additional capital cost for hydronic ceiling radiant panels $170,000
B. Savings in annual energy costs, hydronic vs electric 
radiant panels (see key notes item B that follows) Less than $8000
C. Present value of savings over 30 years (I=7% e=5%) $ 186,600
D. Savings in annual maintenance costs NI
E. Simple payback period (SPB) 21.3 years
F. True payback period (TPB) 27.2 years
G. Net Present Value (NPV) 30 years $ 11,600
H. Investment rate of return – 30 years – based on $ 8,000 p.a. saving.
- Simple (SRR) 4.7 %
- Internal (IRR) 7.5 %
- Adjusted (AIRR) – 7% reinvestment rate 7.2 %