BUILDING ENERGY PERFORMANCE MODELLING Designbuilder – getting startedtzb.fsv.cvut.cz/files/vyuka/125meb,125mec/prednasky1213/... · 2013. 10. 13. · Simple calculation internal

BUILDING ENERGY PERFORMANCE MODELLINGDesignbuilder – getting started

Miroslav UrbanKatedra technických zařízení budovStavební fakulta, ČVUT v Praze

Designbuilder simulation software

British simulation softwarefor checking building energy, carbon, lighting and comfort performanceCalculation with hourly, daily, monthly simulation step

Used Energy Plus calculation engine for dynamic simulationMain typical uses are:

Calculating building energy consumptionThermal 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.

Miroslav Urban, katedra TZB, Fakulta stavební, ČVUT v Praze 11/2011

Calculation energy consumption

Annual, daily, hourly calculation time stepHeating loadCooling 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, hourlycalculation 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, heatrecovery …)

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 constructionsfrom the library).Openings tab: Openings parameters (type of constructions fromthe library).Lighting tab: Type of lighting system, lighting system surfaceamountHVAC tab: parametrs for Heating, cooling, ventilation, humidification systems


DesignBuilder – Activity tab

Activity tad: Defines activities in the building (templates in thelibrary)

Occupancydensity (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 buildingGeneric templatesDefine own construction


DesignBuilder – Openings tab

Defines openings for the building (zone)From glazing templatesOwn openings


DesignBuilder – Lighting tab

You can load generic Lighting data

Simple calculationinternal gains are calculated by dividing the W/m2/100 lux data in the template by the required illuminance level as set on the Activity tabLighting energy (W/m2) = Lighting (W/m2/100 lux) x Design lux level (Activity tab) / 100

Complex calculationcontrol 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 typeDB 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 levelthe 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).



Compact HVAC system type Its possible to define a system type at the zone levelthe heating/cooling systems are defined in DesignBuilderusing Compact HVAC descriptions but modelled in detail in EnergyPlus.

HVAC model option is set to Compact, there are 5 HVAC system types:

Unitary single zoneFan Coil UnitsUnitary multizoneVAVCAV



Compact – HVAC types – Fancoil units



Compact – HVAC types – Unitary single zone



Compact – HVAC types – Unitary multizone



Compact – HVAC types – VAV (variable air volume + CAV (constant air vol.)


Building a model

Creating default data for a modelBefore building a medel is necessary to define templates anddefault 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 atBuilding levelZone levelSurface level


Building a model – model dataSite

Building

Block

Zone

Surface

Opening, wallMiroslav Urban, katedra TZB, Fakulta stavební, ČVUT v Praze 11/2011

Default wall

Wall type 2

Wall type 2

Wall type 2

Opening for wall 2

modification

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.

When you change a setting for acategory this change is ‘inherited’ by all lower levels within the category.

Building a model – default valuesSite

Building

Block

Zone

Surface

Opening, wallMiroslav Urban, katedra TZB, Fakulta stavební, ČVUT v Praze 11/2011

For level below

For level below

For level below

Simulation data

Data from surface

Construction and window to-wall-ratios default values are inherited down to the surface level where the data is actually usedin the calculations.

Building a model – hierarchy

Model data hierarchy


Source: Harvard universityGraduate school of Design

Building a model - geometry

Block typesBuilding block – creating parts of buildingComponent block – no building parts (ground, shading, adiabaticparts)Outline block – for creating building blocks



Building blockrepresents the outer shell of the model or part of the modelA block may be divided internally into any number of zones by drawing partitions and where needed, voids or courtyards can also be incorporated



Component block – 3 types1-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)



Component blockGround: Adiabatic:



Adding Blocksfirst go to the building level (if you are not already there) and click on the Add new block toolthe dimensions of the block are those measured from the outside, the height of the block is the floor-floor height



ZonesZone type in the activity tab:

1-Standard - occupied and heated or cooled.2-Semi-exterior unconditioned - roofspaces, sunspaces, car parks etc3-Cavity - the zone is a cavity such as the glazed cavity within a double facade or a Trombe wall4-Plenum - the zone is a plenum (under the ceiling, technicaldouble floor – for air flow distribution).


Building a model – editing templates

Generic activity templateYou may check the parameters and edit the template

Generic template is lockedCopy the temteplateEdit the templateSave the teplate in to library


Building a model - schedules

SchedulesOccupancy time, operation time for heating, cooling, mechanicalventilation, 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.



7/12 SchedulesProfile by overall picture of an operation schedule

End use of defaults



Compact schedule (energyplus schedule)


Example 1 - Operation ScheduleSCHEDULE: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 ScheduleSCHEDULE: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;


Compact schedule (energyplus schedule) – edit schedule


Simulation

Calculation types:Heating design simulationCooling design simulationSimulation using hourly weather dataCFDDaylighting


Calculation – heating design

Calculation results are typically used to size heatingcomponents systems and their components.

Constant (Steady-state) external temperature set to the winter design external temperatureNo 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.



Setting the design temperature


Go to the “edit” tab go to “Site” level > “Location” > “Winter DesignWeather Data”.

- set outside design temperature

- a 99% design temperature is onethat will be exceeded for 88 hours in a typicalyear

- a 99.6% design temperature isone that will be exceeded for 35 hours in a typical year.


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“



ResultsAveragetemperaturesHeat losses

GlazingWallsOpeningsRoofsExt. VentilationMech. VentilationEtc …


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.



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 onethat will be exceeded for 88 hours in a typical year

- a 99.6% design temperature isone that will be exceeded for 35 hours in a typical year.



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“


Results – hourly fortypical summer day

TemperatuesOperativeRadiantair

Heat gainsCooling loadsDesign Coolingload summary for

Buildingzone



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 at50%RH when consideringnatural ventilation.

Calculation – simulation

Simulating summer design week


At the “Building Level” go to the “Simulations” to perform the “real weatherdata 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”.


Simulating summer design week


Building level

select “5-Subhourly”data display in Data >Interval


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


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 UrbanKatedra technických zařízení budovStavební fakulta, ČVUT v [email protected]

Documents

BUILDING ENERGY PERFORMANCE MODELLING Designbuilder – getting startedtzb.fsv.cvut.cz/files/vyuka/125meb,125mec/prednasky1213/... · 2013. 10. 13. · Simple calculation internal