Lecture 9 Energy Analysis

BLDG / CIVI 390 Building / Civil Engineering Design Project Lecture 9 BLDG / CIVI 390 Building / Civil Engineering Design Project Lecture 9 – Energy Analysis

BLDG / CIVI 390 Building / Civil Engineering Design Project Lecture 9 1 / 40 Energy Analysis, why? a survey of actual energy performance (as opposed to design performance): • buildings on 45° line imply their actual performance is the same as predicted • some buildings do much better than predicted • an equal number of buildings are doing worse [NBI 2008 Energy Performance of LEED® for New Construction Buildings]

BLDG / CIVI 390 Building / Civil Engineering Design Project Lecture 9 3 / 40 Heating / Cooling Load Why do you want to calculate heating / cooling load? • Sizing of equipment? • Knowing the peak heating / cooling energy demand?

BLDG / CIVI 390 Building / Civil Engineering Design Project Lecture 9 4 / 40 Heating / Cooling Load heating load cooling load [NREL: Strategy Guideline: Accurate Heating and Cooling Load Calculations]

BLDG / CIVI 390 Building / Civil Engineering Design Project Lecture 9 6 / 40 Heating / Cooling Load heating load cooling load [NREL: Strategy Guideline: Accurate Heating and Cooling Load Calculations] Outdoor Design Conditions: WMO#: 716120 Lat: 45.50N Long: 73.58W Elev: 73 StdP: 100.45 Time Zone: -5.00 (NAE) Period: 94-10 WBAN: 99999 Annual Heating and Humidification Design Conditions 99.6% 99% DP HR MCDB DP HR MCDB WS MCDB WS MCDB MCWS PCWD ( a ) ( b ) ( c ) ( d ) ( e ) ( f ) ( g ) ( h ) ( i ) ( j ) ( k ) ( l ) ( m ) ( n ) ( o ) (1) 1 -21.7 -19.1 -28.7 0.3 -20.8 -25.9 0.4 -18.4 5.6 -9.1 5.3 -9.2 2.2 10 (1) Annual Cooling, Dehumidification, and Enthalpy Design Conditions DB MCWB DB MCWB DB MCWB WB MCDB WB MCDB WB MCDB MCWS PCWD ( a ) ( b ) ( c ) ( d ) ( e ) ( f ) ( g ) ( h ) ( i ) ( j ) ( k ) ( l ) ( m ) ( n ) ( o ) ( p ) (2) 7 8.0 30.1 22.0 28.6 20.9 27.2 20.1 23.3 28.3 22.3 26.6 21.4 25.5 2.1 190 (2) DP HR MCDB DP HR MCDB DP HR MCDB Enth MCDB Enth MCDB Enth MCDB ( a ) ( b ) ( c ) ( d ) ( e ) ( f ) ( g ) ( h ) ( i ) ( j ) ( k ) ( l ) ( m ) ( n ) ( o ) ( p ) (3) 21.7 16.5 26.1 20.8 15.6 25.2 19.8 14.7 24.2 69.9 28.4 65.9 26.4 62.5 25.5 704 (3) Extreme Annual Design Conditions 1% 2.5% 5% Min Max Min Max Min Max Min Max Min Max Min Max ( a ) ( b ) ( c ) ( d ) ( e ) ( f ) ( g ) ( h ) ( i ) ( j ) ( k ) ( l ) ( m ) ( n ) ( o ) ( p ) (4) 5.0 4.4 4.0 28.2 -23.9 32.7 3.0 1.3 -26.1 33.7 -27.8 34.5 -29.5 35.2 -31.6 36.2 (4) Hours 8 to 4 & 12.8/20.6 2% Coldest month WS/MCDB 2% MCWS/PCWD to 99.6% DB 0.4% 1% 1% MCWS/PCWD to 0.4% DB Enthalpy/MCDB 1% 2% 0.4% Coldest Month Hottest Month Humidification DP/MCDB and HR 99.6% 99% Heating DB 0.4% 0.4% Dehumidification DP/MCDB and HR Extreme Max WB Extreme Annual DB n-Year Return Period Values of Extreme DB n=20 years n=50 years MCTAVISH, QC, Canada Hottest Month DB Range Cooling DB/MCWB Evaporation WB/MCDB Mean Standard deviation n=5 years 0.4% Extreme Annual WS n=10 years 1% 1% 2%

BLDG / CIVI 390 Building / Civil Engineering Design Project Lecture 9 7 / 40 Heating / Cooling Load heating load cooling load [NREL: Strategy Guideline: Accurate Heating and Cooling Load Calculations] Indoor Design Conditions: Heating: 21 °C (70 °F), ~30% RF Cooling: 24 - 26 °C (75 - 78 °F), ~50% RF

BLDG / CIVI 390 Building / Civil Engineering Design Project Lecture 9 9 / 40 Energy Estimating Methods Degree day method • One of the simplest methods of energy analysis and is appropriate if the building use and the efficiency of the HVAC equipment are constant

BLDG / CIVI 390 Building / Civil Engineering Design Project Lecture 9 10 / 40 Degree Day Method Balance Point Temperature: • t bal for a building is defined as the value of outdoor temperature t o at which, for the specified indoor temperature t i , the total heat loss q gain is equal to the heat gain from sun, occupants, light etc.

BLDG / CIVI 390 Building / Civil Engineering Design Project Lecture 9 12 / 40 Degree Day Method Balance Point Temperature: • t bal for a building is defined as the value of outdoor temperature t o at which, for the specified indoor temperature t i , the total heat loss q gain is equal to the heat gain from sun, occupants, light etc. Degree Days:

BLDG / CIVI 390 Building / Civil Engineering Design Project Lecture 9 13 / 40 Heating / Cooling Demand

BLDG / CIVI 390 Building / Civil Engineering Design Project Lecture 9 15 / 40 Thermal Comfort 25°C 25°C ► feel hot ► feel comfortable 25°C ► feel comfortable @500 m ... heat and moisture transfer activities, or ...

BLDG / CIVI 390 Building / Civil Engineering Design Project Lecture 9 16 / 40 Thermal Comfort ► Warm summer day Outside 25°C ► Cold winter night Outside -25°C ► feel warm and comfortable ► feel cold and chilly ► room is maintained at the same 22°C ► what is the difference? 22°C 22°C

BLDG / CIVI 390 Building / Civil Engineering Design Project Lecture 9 18 / 40 Thermal Comfort 25°C 25°C ► feel hot ► feel comfortable 25°C ► feel comfortable @500 m ... are we design a gym?

BLDG / CIVI 390 Building / Civil Engineering Design Project Lecture 9 19 / 40 Thermal Comfort 25°C 25°C 25°C