1. HIGH RESOLUTION MODELLING FOR PERFORMANCE ASSESSMENT OF FUTURE DWELLINGS
Nick Kelly, Jon Hand,
Aizaz Samuel
ESRU, University of Strathclyde, Glasgow

2. Overview temporal resolution in building simulation (BS)
previous work with high temporal resolution simulations
improving resolution in building simulation
electrical power
hot water
solar radiation
what difference does it make?
conclusions and further work

3. Temporal Resolution in Building Simulation
BS grounded in modelling of building thermal performance
some physical processes with longer time constants e.g. heat conduction in constructions
many tools (by default) run at hourly resolution
however, scope of building simulation increasing
HVAC systems
renewables
control
lighting
electrical
are longer time-step simulations sufficient?

4. Some Previous Work – Lighting Simulation
simulation of lighting controller at 60-min and 5-min resolution using real hourly and stochastic 5-min solar data (Clarke & Janak 1998)
as BS evolves to model more processes in buildings can modelling at higher resolution bring benefits?
… also what are the constraints?

5. Temporal Resolution in Building Energy Modelling
in a temperate climate like the UK solar radiation can change rapidly with time due to cloud transit across the sun
BS typically uses hourly averaged solar data

6. Temporal Resolution in Building Energy Modelling
resulting PV output

7. Temporal Resolution in Building Energy Modelling
electrical demand characterised by rapid fluctuation

8. Temporal Resolution in Building Energy Modelling
hot water draws also typically short duration and highly variable

9. Improving Temporal Resolution
many BS tools can already operate at sub-hourly resolution
achieving higher temporal resolution in BS often question of data and models
here we look at how ESP-r has been adapted to accommodate high resolution data
and possible impact higher resolution has on predictions

10. Solar Data ESP-r’s default climate database holds hourly data
sub-hourly time steps interpolation is used
temporal definition database (TDF) can hold sub-hourly data (either real or generated)
tool developed to generate sub hourly data from hourly datasets (1st order Markov model) [1]
transition probabilities need to be calibrated using measured high resolution data
[1] McCracken D Synthetic High Resolution Solar Data, MSc Thesis, University of Strathclyde, Glasgow.

11. Solar Data

12. Electrical Demand
tool developed by Richardson [2] adapted to pre-simulate annual domestic electrical demand at 1-min resolution
… and corresponding thermal gains
pre-simulated data held in TDF
used as a boundary condition by ESP-r’s electrical systems solver
[2] Richardson I, Thompson M, Infield D, Clifford C Domestic electricity use: A high-resolution energy demand model. Eng. and Build. 4210) pp

13. Hot Water Draws
work of Jordan and Vagen [3] (IEA SHC Annex 26) used to generate new stochastic hot water draw component in ESP-r
determines if hot water draw takes place ,draw flow rate and duration at each simulation time step (at up to 1-min resolution)
model also used as basis of draw profiles generated in IEA ECBCS Annex 42
[3] Jordan U and Vajen K, DHWCALC: Program to Generate Domestic Hot Water Draws with Statistical Means for User Defined Conditions, Proc. ISES Solar World Congress, Orlando, US.

14. What Difference Does it Make?
comparison of results from ‘Zero Energy’ building simulated at 1-min and 60-min resolution

15. What Difference Does it Make?
‘Zero Energy’ building simulated at 1-min and 60-min resolution

16. What Difference Does it Make?
Power import/export

17. What Difference Does it Make?
DHW & heating

18. What Difference Does it Make?

19. Conclusions
many processes occurring in buildings occurring at high resolution
hourly averaged boundary data fails to capture characteristics e.g. variability of solar radiation, electrical demand and import/export of electricity
ESP-r adapted to utilise higher resolution boundary data
tools developed/adapted to generate high resolution solar data, appliance demand/thermal gains and hot water draws
[3] Jordan U and Vajen K, DHWCALC: Program to Generate Domestic Hot Water Draws with Statistical Means for User Defined Conditions, Proc. ISES Solar World Congress, Orlando, US.

20. Conclusions
simulation of hypothetical zero energy building – passive house insulation, PV array, heat pump, MVHR.
little difference in energy performance of heat pump and hot water systems (thermal buffering)
unbuffered simulations show short duration cycling
differences in PV output (thermal/electrical dependencies)
significant difference in electrical import export and self consumption
suggests higher resolution preferable for modelling of microgeneration and involving interaction with electrical network

21. Further Work this presentation has focused on solar and HVAC processes
however high resolution modelling perhaps also appropriate for modelling of wind driven infiltration (e.g. typical gust duration 10s)
… also air movement in buildings, modelling of control action, air conditioning.

22. Further Work
and calculating maximum electrical demand

23. Acknowledgements
this work was undertaken as part of the UKRC Energy Programme - Grand Challenge in Energy Systems: Top and Tail Transformation

24. Thank you!