Unformatted text preview: ents using a “componentbased” approach. For example:
• Exterior walls shall have a minimum thermal
resistance of R-15.
• Office spaces shall have maximum lighting power
density of 10 W/m2.
• Washroom faucets in public building shall have
automatic shut-off (e.g. to conserve hot water).
Note: The above are only examples of the types of requirements.
(The actual requirements for each component are listed within
the code/standard.) Aside:
Code requirements are typically based on cost-effective
good-practice for “typical” building conditions.
However, for some specialized building types, application
of the code requirements may not be suitable/practical. (End of Aside.) Both codes used two basic types of requirements:
• A minimum level of performance that must be met by all
• Define a “reference level” of performance.
• Comply either by meeting each individual prescriptive
requirement, or by demonstrating the design will not use
more energy than a design that did meet each individual
• Provides some flexibility in design (“trade-offs”). STRUCTURE OF MNECB 1997
Envelope Lighting Service
Water Htg HVAC Prescriptive Path Electrical
& Power Performance Path Building Envelope
Building Energy Performance
Heating REDESIGN Compliance?
YES Example of Application of Mandatory and Prescriptive
Imagine an extremely simple building where applicable code
provisions are only as follows:
1. Maximum allowable flow-rate of shower-heads is
1. Maximum thermal transmittance (U-value) of
exterior walls = 0.38 W/m2-°C.
2. Minimum efficiency of furnace = 85%. outdoors
flue Furnace Heated Space fuel heat loss through
exterior wall with
thermal transmittance = heat input from heating device
with efficiency = Mandatory Provisions…
Shower-head flowrate must be 9.0 L/min or less. (Cannot
“trade-off” versus other provisions.) Any design with
showerhead flowrate higher than 9.0 L/min would not
comply—no matter how “efficient” the other components
of the building were made. Prescriptive Provisions…
Characteristic Design A Design B Design C Design D Wall U-value
(W/m2-°C) 0.38 0.30 0.30 0.50 Furnace
Efficiency 85% 85% 80% 95% Complies? Yes. Yes. ? ? Prescriptive Performance
Method? Prescriptive “Reference Design”
Compare to performance of “Reference Design”
(i.e. design that exactly meets prescriptive
provisions) Sample Requirements from MNECB 1997:
Vestibules are required at exterior doors. (Some doors are exempted
from this requirement—as described in the Code).
Maximum Overall Thermal Transmittance (U-value), W/m2-°C
“Ontario Region A” (Southern Ontario)
Above Ground Walls Heating Source
Electricity Natural Gas 0.330 0.550 Sample Requirements from MNECB 1997:
Exterior lights shall be controlled by a lighting schedule controller
(timer) or by a photocell (daylight sensor).
Maximum Allowable Lighting Power Density (W/m2) by Space-Type
Space Type LPD (W/m2) Laboratory 24.8 Classrooms 21.5 Gymnasium 10.8 Jail Cell 8.6 Sample Requirements from MNECB 1997:
Systems shall have controls capable of reducing energy use through
temperature set-back or equipment shut-down during periods of
non-use (with some exceptions).
HVAC systems shall utilize outside-air economizers (with some
exceptions). Sample Requirements from MNECB 1997:
SERVICE WATER HEATING
Faucets in public access washroom shall have a device capable of
automatically shutting off the flow of water when the faucet is not in
use (e.g. motion sensor or spring-return valve). ELECTRICAL POWER
Electrical transformers shall conform to CAN/CSA-C802 “Maximum
Losses for Distribution, Power, and Dry-Type Transfomers” where the
installed transformer falls within the scope of the standard.
(CAN/CSA-C802 includes minimum requirements for transformer
efficiency.) Typical Procedures for
“Performance Compliance Analysis”
• Usually hour-by-hour simulations are performed to
compare performance of “proposed design” vs the
code “reference design” (i.e. prescriptive design)
• In general, any characteristics not covered by
Prescriptive Requirements are treated identically
– Size and use of building
Operating schedules (occupants, lighting, plug loads, etc)
Minimum fresh air rates (ventilation)
Area and orientation of exterior envelope components
(with some exceptions) For Example: “EE4” Software
• Hour-by-hour simulation tool intended
comparing “Proposed Design” to MNECB for • Simulator describes characteristics of the “Proposed
– Software performs simulation of the “Proposed Design”
– Software automatically creates a second simulation file –
the “Reference Design” simulation, which is identical to
the proposed design, except that it uses the relevant
View Full Document
This note was uploaded on 10/04/2012 for the course ME 760 taught by Professor Davidmather during the Spring '12 term at Waterloo.
- Spring '12