BUILDING ENERGY PERFORMANCE MODELLING Designbuilder getting started Miroslav Urban Katedra technických zařízení budov Stavební fakulta, ČVUT v Praze
Designbuilder simulation software British simulation software for checking building energy, carbon, lighting and comfort performance Calculation with hourly, daily, monthly simulation step Used Energy Plus calculation engine for dynamic simulation Main typical uses are: Calculating building energy consumption Thermal simulation of naturally ventilated buildings. Daylighting - models lighting control systems and calculates savings in electric lighting. Visualisation of site layouts and solar shading. Calculating heating and cooling equipment sizes.
Calculation energy consumption Annual, daily, hourly calculation time step Heating load Cooling load
Visualisation of solar shading Shading and daylight calculation
Visualisation of solar shading
Temperatures calculation Operative, mean radiant and air temperature
DesignBuilder - overview Model Data Hierarchy organised in a simle hierarchy
DesignBuilder - input data, hierarchy Default data is inherited from the level above in the hierarchy, block data is inherited from building level, zone data is inherited from block data and surface data from zone data. Activity, Lighting, HVAC, Equipment data is used at the zone level, i.e. all Activity, Lighting, HVAC, Equipment data at building and block level is default data. Construction and Openings data is used at the surface level, i.e. all construction and opening data at building, block and zone level is default data and only data at surface level is actually used to define the model.
DesignBuilder - results Energy simulation detailed results (Daily, mothly, hourly calculation step) At zone level: Environmental/Comfort Output average from a zone (Air temperature, MR temperature, operative temperature, PMV) Fabric and ventilation (heat gains) Airflow (HVAC air distr. Systém, infiltration, natural ventilation) System heat flows (zone heating/cooling, AHU heating, heat recovery ) At building level: Fuel breakdown (heat generation, total energy for chiller, electricity for pumps, fans,) Fuel totals (Total fuel consumption for building)
DesignBuilder getting started Creating of the building model in DB Before creating model in DB collect input data for SW Activity tab: Activities in the building (templates in the library). Construction tab: Construction parameters (type of constructions from the library). Openings tab: Openings parameters (type of constructions from the library). Lighting tab: Type of lighting system, lighting system surface amount HVAC tab: parametrs for Heating, cooling, ventilation, humidification systems
DesignBuilder Activity tab Activity tad: Defines activities in the building (templates in the library) Occupancy density (people / m2), occupation schedule (day, hour), metabolic rate (calculation comfort) Heat gains (computers, lighting, other) Envinmental control HVAC setpoint temperatures, schedules, minimum fresh air, etc.
DesignBuilder Construction tab Construction tab defines construction of building Generic templates Define own construction
DesignBuilder Openings tab Defines openings for the building (zone) From glazing templates Own openings
DesignBuilder Lighting tab You can load generic Lighting data Simple calculation internal gains are calculated by dividing the W/m 2 /100 lux data in the template by the required illuminance level as set on the Activity tab Lighting energy (W/m 2 ) = Lighting (W/m 2 /100 lux) x Design lux level (Activity tab) / 100 Complex calculation control the electric lights according to the availability of natural daylight.
DesignBuilder HVAC tab Defines HVAC systems fot the building (zone) Simple or Compact HVAC system type DB can automatically calculate heating and cooling capacity in each zone based on the output from the Heating and Cooling design calculations. Simple HVAC system type only on the building level the heating/cooling system is modelled using basic loads calculation algorithms. System type (convective or convective/radiant). Supply air temperatures for simulation. HVAC auxiliary data (below).
DesignBuilder HVAC tab Compact HVAC system type Its possible to define a system type at the zone level the heating/cooling systems are defined in DesignBuilder using Compact HVAC descriptions but modelled in detail in EnergyPlus. HVAC model option is set to Compact, there are 5 HVAC system types: Unitary single zone Fan Coil Units Unitary multizone VAV CAV
DesignBuilder HVAC tab Compact HVAC types Fancoil units
DesignBuilder HVAC tab Compact HVAC types Unitary single zone
DesignBuilder HVAC tab Compact HVAC types Unitary multizone
DesignBuilder HVAC tab Compact HVAC types VAV (variable air volume + CAV (constant air vol.)
Building a model Creating default data for a model Before building a medel is necessary to define templates and default data for a building Activity templates (for each different zone) Construction templates (for each construction) Openings templates (different glazing, glazing layout, frame..) HVAC templates (fancoil system, etc ) Default data at Building level Zone level Surface level
Building a model model data Default data is inherited from the level above in the hierarchy, so block data is inherited from building level, zone data is inherited from block data and surface data from zone data. modification Default wall Wall type 2 Site Building Block When you change a setting for a category this change is inherited by all lower levels within the category. Wall type 2 Wall type 2 Zone Surface Opening for wall 2 Opening, wall
Building a model default values Construction and window towall-ratios default values are inherited down to the surface level where the data is actually used in the calculations. For level below For level below Site Building Block For level below Zone Simulation data Surface Data from surface Opening, wall
Building a model hierarchy Model data hierarchy Source: Harvard university Graduate school of Design
Building a model - geometry Block types Building block creating parts of building Component block no building parts (ground, shading, adiabatic parts) Outline block for creating building blocks
Building a model - geometry Block types Building block creating parts of building Component block no building parts (ground, shading, adiabatic parts) Outline block for creating building blocks
Building a model - geometry Building block represents the outer shell of the model or part of the model A block may be divided internally into any number of zones by drawing partitions and where needed, voids or courtyards can also be incorporated
Building a model - geometry Component block 3 types 1-Standard - used for shading, reflection and visualisation balconies, pillars, shading obstructions (show in blue) 2-Ground - used for setting ground adjacency, shading, reflection and visualisation ground modelling, to modify the adjacency of the surfaces touching it to be 'adjacent to ground (show in green) 3-Adiabatic - used for setting adiabatic adjacency, shading, reflection and visualisation Adiabatic surfaces do not transfer heat beyond their outer surface and are often used for modelling boundaries with other spaces (show in red)
Building a model - geometry Component block Ground: Adiabatic:
Building a model - geometry Adding Blocks first go to the building level (if you are not already there) and click on the Add new block tool the dimensions of the block are those measured from the outside, the height of the block is the floor-floor height
Building a model - geometry Zones Zone type in the activity tab: 1-Standard - occupied and heated or cooled. 2-Semi-exterior unconditioned - roofspaces, sunspaces, car parks etc 3-Cavity - the zone is a cavity such as the glazed cavity within a double facade or a Trombe wall 4-Plenum - the zone is a plenum (under the ceiling, technical double floor for air flow distribution).
Building a model editing templates Generic activity template You may check the parameters and edit the template Generic template is locked Copy the temteplate Edit the template Save the teplate in to library
Building a model - schedules Schedules Occupancy time, operation time for heating, cooling, mechanical ventilation, lighting, temperature setpoints You can define schedules in one of 2 ways: 7/12 Schedules - where each day of the week and each month of the year has a unique daily variation defined using profiles. Compact Schedules - more flexible definition using EnergyPlus Schedule: Compact text-based data format.
Building a model - schedules 7/12 Schedules Profile by overall picture of an operation schedule End use of defaults
Building a model - schedules Compact schedule (energyplus schedule) Example 1 - Operation Schedule SCHEDULE:COMPACT, Office_CellOff_Light, Fraction, Through: 31 Dec, For: Weekdays SummerDesignDay, Until: 07:00, 0, Until: 19:00, 1, Until: 24:00, 0, For: Weekends, Until: 24:00, 0, For: Holidays WinterDesignDay AllOtherDays, Until: 24:00, 0; Example 2 - Temperature Setpoint Schedule SCHEDULE:COMPACT, Bedroom_Cool, Temperature, Through: 31 Dec, For: Weekdays SummerDesignDay, Until: 05:00, 0.5, Until: 09:00, 1, Until: 17:00, 0.5, Until: 24:00, 1, For: Weekends, Until: 05:00, 0.5, Until: 24:00, 1, For: Holidays WinterDesignDay AllOtherDays, Until: 24:00, 0;
Building a model - schedules Compact schedule (energyplus schedule) edit schedule
Simulation Calculation types: Heating design simulation Cooling design simulation Simulation using hourly weather data CFD Daylighting
Calculation heating design Calculation results are typically used to size heating components systems and their components. Constant (Steady-state) external temperature set to the winter design external temperature No solar gain. No internal gains (lighting, equipment, occupancy etc). Heated zones are heated constantly to achieve the heating temperature set point using a simple convective heating system. Includes consideration of heat conduction and convection between zones of different temperatures. Schedules are not used for Heating design calculations which are based on a steady state analysis which does not account for timing.
Calculation heating design Setting the design temperature Go to the edit tab go to Site level > Location > Winter Design Weather Data. - set outside design temperature - a 99% design temperature is one that will be exceeded for 88 hours in a typical year - a 99.6% design temperature is one that will be exceeded for 35 hours in a typical year.
Calculation heating design Sizing factor The Heating Design margin is used to multiply calculated steady state heating loads in each zone to give a recommended heating plant size. Set 1,2
Calculation heating design Results Average temperatures Heat losses Glazing Walls Openings Roofs Ext. Ventilation Mech. Ventilation Etc
Calculation cooling design Cooling design calculations are carried out to determine the capacity of mechanical cooling equipment required to meet the hottest summer design weather conditions Periodic steady-state external temperatures calculated using maximum and minimum design summer weather conditions. No wind. Includes solar gains through windows and scheduled natural ventilation. includes internal gains from occupants, lighting and other equipment. Includes consideration of heat conduction and convection between zones of different temperatures.
Calculation cooling design Setting cooling design temperature Go to the edit tab go to Site level > Location > Summer Design Weather Data. - set outside design temperature - a 99% design temperature is one that will be exceeded for 88 hours in a typical year - a 99.6% design temperature is one that will be exceeded for 35 hours in a typical year.
Calculation cooling design Sizing factor The Summer Design margin is used to multiply calculated steady state heating loads in each zone to give a recommended heating plant size. Set default 1,3
Calculation cooling design Results hourly for typical summer day Temperatues Operative Radiant air Heat gains Cooling loads Design Cooling load summary for Building zone
Calculation cooling design Analyzing temperature profiles without mechanical cooling radiant temperature (red) operative temperature (green) air temperature (blue) outside temperature (dark blue) The operative temperature is also above the comfort temperature of 24 C-27 C recommended by ASHRAE STD 55 and ISO 7730 at 50%RH when considering natural ventilation.
Calculation simulation Simulating summer design week At the Building Level go to the Simulations to perform the real weather data simulation. When you first select Subhourly weather data for a Summer Design Week calculation, you will be prompted to download the hourly from DesignBuilder web site. Select OK.
Calculation simulation Simulating summer design week Building level select 5-Subhourly data display in Data > Interval
Calculation simulation Annual simulation - results Building level/zonel level select 1-Annual data display in Data > Interval Note: Monthly simulation select 2-monthly data display in Data > Interval
Calculation simulation Daily simulation - results Building level/zonel level select 3-Daily data display in Data > Interval
Results Customizing results At the Building Level, select Data 1-All data display, then go to the Detailed tab in the Display Options.
Conclusion Preparing and running a simulation takes time. Before rushing into doing a simulation you should have a clear idea of how the simulations results can help you resolve a specific design question that you could not answer otherwise. Always consider that buildings are a complex integration of energy flows and systems comprising not only the whole of building form and fabric, but also plant and various other environmental control systems.
Literature, Questions DesignBuilder>>Help>>Content. www.designbuilder.co.uk/helpv3/ Knowledgebase section in DesignBuilder s webpage which has answers to most common questions about DB. go to: www.designbuilder.co.uk>support>knowledgebase. DesignBuilder Forum - users post all sorts of questions which are usually answered by DesignBuilder software developers. go to: www.designbuilder.co.uk>support>designbuilder Forum.
Miroslav Urban Katedra technických zařízení budov Stavební fakulta, ČVUT v Praze miroslav.urban@fsv.cvut.cz