Post on 06-May-2018
Building the Future
Thermal Modelling of Buildings
Chris KendrickOISD: technologyOxford Brookes University
January 2008
Why?
• Whole building performance: thermal comfort, energy and CO2
• Passive/Bioclimatic design strategies: solar, natural ventilation
• Optimisation of design (what if…?)
• Building details: thermal bridging, condensation
• Regulation: Building Regulations Part L
Solar radiation
Heating
Cooling
Mechanical ventilation
Artificial light
Through envelope
Equipment and human emissions
Dynamic thermal simulation
• Model whole building performance
• Real recorded weather data
• Internal temperatures, ventilation rates, heating and cooling energy consumption, solar gains
1 5 J u n 1 4 : 0 0
N suneye
Suncast image: View time = 15 Jun 14:00
Site Latitude = 52.17
Longitude diff. = 5.97
Model Bearing = 110.00
Sun: azi = 237.38 alt = 50.24
Eye: azi = 180.00 alt = 30.00
Dynamic thermal simulation
36.28622.66629.4730121.82Total
3.0821.8895.408028.536Dec
2.9821.8395.209019.598Nov
3.0821.9763.106.259Oct
2.9821.839000Sep
3.0821.932000Aug
3.0821.932000Jul
2.9821.839000Jun
3.0821.9760.15800.16May
2.9821.8391.52802.457Apr
3.0821.8893.491010.868Mar
2.7841.744.894024.131Feb
3.0821.9765.686029.812Jan
Equip.Lights
Auxiliary (fans,
pumps, controls)
Cooling (chillers etc.)
Heating (boilers
etc.)Month
Energy totals in MWh
Building systems energy summary
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan
60
50
40
30
20
10
0
-10
-20
Tem
pera
ture
(°C
)
Date: Fri 01/Jan to Fri 31/Dec
Dry-bulb temperature: (warsaw flats2.aps) Dry resultant temperature: f3 block3 (warsaw flats2.aps)
Dynamic thermal simulationNatural Ventilation
Bulk air movement model (zone to zone)
Two dimensional CFD modelling of zone
Thermal comfort
Dynamic thermal simulation
0
5
10
15
20
25
30
35
>20 >21 >22 >23 >24 >25 >26 >27 >28 >29 >30 >31 >32 >33 >34 >35
Deg C
% o
ccup
ied
hour
s
Ambient
Warehouse left 250Lux 10W/m2 DF6.381
Warehouse right 250Lux 10W/m2 DF8.017
Warehouse left 250Lux 5.6W/m2 DF6.381
Warehouse right 250Lux 5.6W/m2 DF8.017
• 3D representation of building and apertures
• Application of sky illuminance for desired latitude
• Calculation of daylight factors over desired plane for each hour
• Daylight rendering
Daylighting analysis
0-300 300-600 600-900 900-12001200-1500 1500-1800 1800-2100 2100-2400
Conduction analysis
• Model building details
• Steady state or dynamic boundary conditions
• Surface temperatures (condensation risk)
• Linear thermal bridging
Future Developments: Dynamic thermal simulation
• Integrated building performance modelling
• Import CAD geometry directly to thermal model
• Building physics module for CAD?- Ecotect- Revit Architecture (plug-in module)
• Improved graphics and animations
Future Developments: Conduction Modelling
• Direct use of CAD geometry- three dimensional representation of curves, slopes
• Import dynamic boundary conditions from building simulation programs
• Improved graphic user interfaces
• Faster computation times
Summary
• Thermal Modelling is being used increasingly to design better buildings
• Essential for passive/bioclimatic design to reduce mechanical inputs for heating and cooling
• Potential to optimise building performance in future climate change scenarios
• Simulation is set to become embedded into the design process as designers strive to achieve zero carbon buildings