heat exchanger which preheats the inlet air before it enters the living spaces. This will help us
decrease the use of heat pumps.
2.0 House, Appliances and HVAC Simulations (Annual Simulation)
2.1 Simulation Tools Description
The building energy modeling tool used for this project is DesignBuilder, developed by DesignBuilder Software Ltd located in the United Kingdom. For accurate energy analysis, DesignBuilder uses the Ener-gyPlus dynamic thermal simulation engine developed under the U.S. Department of Energy. For Orchid House, DesignBuilder was used to model internal temperature fluctuations, HVAC loading, and heat balance (relationship between time and heat gain/loss). The simulation results generated by Design-Builder aided the project team in developing passive design strategies, operational schedules, systems and materials selection, and evaluate building efficiency. The limitation with using DesignBuilder is a less accurate Computational Fluid Dynamics (CFD) simulation needed to model natural ventilation and air flow within the project building.
TRANSYS Simulation Program is adopted for the HVAC Simulation. Three portions of HVAC system have been done:
1. Heat pump energy consumption for both space cooling and heating.
2. Energy recovery ventilator to reclaim the thermal energy, sensible and latent heat, from the exhaust air.
3. Solar thermal system to provide a limited amount of energy for space heating.
The results of simulation including the input and output data, and the summary are shown in Appendix B.
2.2 Housing Unit Modeling: internal gains, occupancy behavior patterns, ventilation and com-fort temperature
1. Modeling Methodology and Zoning
Before energy simulation can be performed, a model of the project building is created first. We used Autodesk Revit to build the design model of Orchid House, and then through format conversion (gbXML – Green Building XML Schema), the model was transferred to the DesignBuilder platform. The advan-tage of using separate software platforms is the ability to leverage the comparative strengths and apply it into the simulation process. Revit is a prevalent and powerful BIM tool that allows for the data entry of individual building components. For example, during the placement of a wall, parameters such as wall thickness, layer composition and physical properties can easily be inputted. When transferred to DesignBuilder this data is used by the energy analysis algorithm to derive the thermal properties of the wall. This is applied to every building component throughout the model, to create an accurate physi-cal environment for energy simulation. In addition, Revit software has the feature to input individual Thermal Zones, allowing for the analysis of individual areas, and also allows easy creation of building openings, glazing, and shading devices. Figures 5.4.2.2.2b ~ 2d show the individual Thermal Zones and building openings in the DesignBuilder software.
Figure 5.4.2.2.2a The transfer process between Revit and DesignBuilder by gbXML simplifies the model and removes irrelevant information which allows for more efficient energy simulation
Figure 5.4.2.2.2b A visualization of the DesignBuilder energy model
Figure 5.4.2.2.2c Ground Floor thermal zones and building openings in DesignBuilder
Figure 5.4.2.2.2d Second Floor thermal zones and building openings in DesignBuilder
2. Material Thermal Properties
Asides from the physical properties of materials that get transferred from Revit to DesignBuilder, ad-ditional thermal properties must be inputted for these materials to perform accurate energy analysis.
Thermal properties for building materials are obtained from:
• Test reports provided by materials manufacturers
• Green building reference guides such as the British Chartered Institution of Building Services Engineers Guide A or Taiwanese Green Building Standards.
The thermal properties for building materials used in Orchid House are as follows:
Layer Insulation Type Thickness
Inner Plywood 6.00 0.13 2500.00 560.00
Plywood 12.00 0.13 2500.00 560.00
VIP 30.00 0.01 687.00 177.00
Glass Foam 130.00 0.07 840.00 117.00
Plywood 24.00 0.13 2500.00 560.00
Outer Plywood 6.00 0.13 2500.00 560.00
Second Floor
Layer Insulation Type Thickness (mm)
Outer Polycarbonate 40.00 0.04 1200.00 1200.00
Air 60.00 0.02 1008.00 1.23
Plywood 24.00 0.13 2500.00 560.00
Glass Foam 65.00 0.07 840.00 117.00
VIP 30.00 0.01 687.00 177.00
Plywood 12.00 0.13 2500.00 560.00
Inner Plywood 6.00 0.13 2500.00 560.00
1F Wall(East+West)
Layer Insulation Type Thickness (mm)
Outer Polycarbonate 10.00 0.03 1200.00 1200.00
Air 40.00 0.02 1008.00 1.23
PET 3.00 0.51 1000.00 1370.00
Water 250.00 0.58 4190.00 990.00
PET 3.00 0.51 1000.00 1370.00
Polycarbonate 10.00 0.03 1200.00 1200.00
Air 40.00 0.02 1008.00 1.23
Inner Plywood 40.00 0.13 2500.00 560.00
Thermal Wall
Layer Insulation Type Thickness (mm)
Outer Polycarbonate 15.00 0.03 1200.00 1200.00
Air 10.00 0.02 1008.00 1.23
Inner Polycarbonate 15.00 0.03 1200.00 1200.00
2F Wall(East+West)
Layer Insulation Type Thickness (mm)
Outer Polycarbonate 3.00 0.0280 1200.00 1200.00
Air 10.00 0.0240 1008.00 1.23
Inner Polycarbonate 3.00 0.0280 1200.00 1200.00
PLYCARBONATE ROOF
Layer Insulation Type Thickness
Inner Plywood 6.00 0.13 2500.00 560.00
Plywood 12.00 0.13 2500.00 560.00
VIP 30.00 0.01 687.00 177.00
Glass Foam 130.00 0.07 840.00 117.00
Plywood 12.00 0.13 2500.00 560.00
Outer Plywood 6.00 0.13 2500.00 560.00
Interior partition
Layer Insulation Type Thickness (mm)
Soda lime glass 10.00 1.00 750.00 2500.00
ROOF-PV Panel
Layer Insulation Type Thickness (mm)
Thermal Conductivity
(W/m².K)
Specific Heat
(J/kg-k) SHGC VLT Density
(Kg/m²)
熱傳導率-U值 (W/m².K)
Outer Polycarbonate 3.00 0.03 1200.00 1200.00 9.33
Air 4.00 0.02 1008.00 1.23 6.00
Inner Polycarbonate 3.00 0.03 1200.00 1200.00 9.33
Transparent panel(10mm)
0.43 0.42
Layer Insulation Type Thickness (mm)
Thermal Conductivity
(W/m².K)
Specific Heat
(J/kg-k) SHGC VLT Density
(Kg/m²) 熱傳導率-U值
(W/m².K)
Polycarbonate 6.00 0.03 1200.00 0.63 0.65 1200.00 4.67
Transparent panel(6mm)
3. Interior Gains
The energy model includes various inputs for heat gains such as appliances, lighting fixtures and occu-pancy. Affecting these inputs includes other constraints such as power consumption, operating sched-ule and thermal emissions. For appliances and lighting fixtures, the main parameters investigated for Orchid House are the energy rate and heat gain fraction. However, since there are few reference docu-ments for appliance and lighting heat gain fraction, the following assumptions were used for the en-ergy model:
Interior gains – Appliance Space Product Name Energy
rate(w)
Heat gain fraction Fraction
• The Radiant fraction is the fraction of heat emitted by the device as long-wave radiation.
• The Latent fraction is the fraction of the rated power which is converted to latent energy and af-fects the moisture balance in the zone instead of the sensible heat balance.
• Fraction heat lost is the fraction of the sensible heat emitted which is lost or vented directly to outside without affecting the zone heat balance.
• Fraction Convective = 1.0 – (Fraction Latent + Fraction Radiant + Fraction Lost)
The occupancy of Orchid House is set as the common Taiwanese household of Husband and Wife duo couple with the following metabolic rates (thermal emissions):
4. Occupancy Behavior Pattern
Occupancy rate and behavior will reflect the operation schedule and energy consumption of the appli-ances and various fixtures within the model house. Therefore, setting a believable mode of occupancy behavior becomes vital for achieving accurate energy simulation. Based on a Taiwanese research re-port “A study on the Energy Consumption Certificate of Residential Buildings”, the author created a statistical model for the average Taiwanese household occupancy rate and behavior. Referencing these results the following occupancy schedule was created and used for the energy model of Orchid House in Taiwan setting.
• Metabolic rate data according to ASHRAE Handbook of Fundamentals, Chapter 8,Table 5.
Interior gains –Lighting fixtures Space Product Name Energy
rate(w)
Heat gain fraction Fraction
Interior gains – Occupancy
Space Occupancy Metabolic
Metabolic rate (w/person) Factor
Measurable area 2 126 0.9