*Heating: Explanation of choices
Select the best energy available at the best cost
In the first drafts, an all-electric strategy was envisaged, but given the requirement for boiler redundancy in case of power outages, huge capacity generators would have been required.
Using gas-fired boilers/water heaters allows an appreciable reduction in the capacity of the generators and an average investment saving of about $4 M compared with the use of 100% electric boilers.
Besides considerably reducing capital costs, natural gas boilers also allow savings in the operating costs of managing electricity peaks.
Optimize peak management
When natural gas is available, gas-fired boilers/water heaters are used to manage electricity peaks, respecting criteria 2 & 3 of CCAP 2020.
Peak management allows a quite significant energy saving of about $5/m2, which translates into an average annual saving of $26,000 for a 48-bed MDA, $40,000 for a 72-bed MDA, and $52,000 for a 96-bed MDA. The saving comes from reducing the monthly peak and removing the applicability of the penalty imposed by Rate M.
Note: This peak management strategy is not used for buildings that use propane because of the high costs of propane compared with natural gas.
Technologies envisaged but not retained
| Technology |
Decisions |
| Geothermal |
Too many risks are associated with the non-repeatability of the solution, which is dependent on worksite conditions and soil typologies. |
| Aerothermal |
Impracticable in a cost-management context. |
| Heat recovery from chillers |
Little potential, given the high heat recovery from exhaust air by the heat exchangers, as well as the shape of the buildings. |
Solutions from the concept teams
According to the concept teams, certain variabilities can be observed on the various projects, the most important being:
- 100% outdoor air systems with heat recovery
- Recovery chillers
- Heat recovery on outdoor air with lower efficiencies
- Single duct systems with electric terminal reheat to ensure comfort
