Reference SHW Configuration Guidance NECB 2017

While some predefined elements have been provided to the user through the NECB navigator e.g. fuel fired SHW plant in ApacheHVAC, the configuration of the reference SHW system needs to be compiled by the user. The following notes provide guidance on the reference configuration:

Table 6.2.2.1 states the equipment performance requirements:

Section 8.4.4.2.(2) states:

· The reference building's internal and service water heating loads shall be modelled as being identical to those determined for the proposed building in Sentence 8.4.3.2.(2).

Section 8.4.4.6.(3) states:

· Where a primary service water heating system of the proposed building uses purchased energy, the reference building's corresponding system shall be modeled in accordance with the requirements of Article 8.4.4.20. adjusted as follows:

A. One gas fired service water heater shall be used to represent the purchased energy equipment,

B. Where the proposed buildings purchased energy system is used to heat service water in a heater with a storage tank the service water heater shall have the same storage capacity and,

C. The total capacity of the service water heaters, relative to the reference building's total service water heating capacity, shall correspond to the ratio of the proposed building's purchased energy capacity divided by its total heating capacity.

Section 8.4.4.20 states:

· Except as provided in Sentences (2) to (4), the reference building's service water heating system shall be modeled as being identical to that of the proposed building as regards the following characteristics:

A. Storage capacity

B. Power input, and

C. Energy type

· Where the energy type of the proposed building's service water heating system is an air-, water- or ground-source heat pump, the energy type of the reference building's service water heating system shall be an air-source heat pump.

· Where the energy type of the proposed building's service water heating system is an immersion coil supplied by a boiler, the energy type of the reference building's service water heating system shall be the same as that of the boiler.

· Where more than one energy type is used by the proposed building's service water heating system

A. the heating capacities of the reference building's service water heating equipment shall match the ratio of the proposed building's service water heating equipment capacity allocation, and

B. the operating schedule, priority of use and other operational characteristics of the proposed building's use of energy types shall apply.

· Service water heating equipment performance characteristics as a function of part-load shall be modeled in accordance with the part-load performance curves found in Table 8.4.4.21.G. These have been provided in ApacheHVAC.

· The service water heating system's supply temperature shall be modeled as being identical to that of the proposed building.

· Where a storage tank is to be modeled, the service water heating system's storage temperature shall be modeled as being identical to that of the proposed building.

· Where the proposed building's service water heating system comprises multiple water heaters, the reference building's service water heating system shall be modelled with the same number of water heaters.

· Where the proposed building's service water heating system is a recirculation system, the circulation pumps shall be modeled as

A. constant speed operation, and

having a flow rate and pumping power, in W/(L/s) that is identical to that of the proposed building's circulation pumps.