BERS Pro Plus 4.2 New Features and Modelling Changes. Holger Willrath Solar Logic October 2011

Transcription

1 BERS Pro Plus 4.2 New Features and Modelling Changes Holger Willrath Solar Logic October 2011

2 BERS Pro Plus V4.2 New Features and Modelling Changes Holger Willrath Solar Logic This document may not be reproduced in printed or electronic form Student Notes New Features and Modelling Changes BERS Pro Plus 4.2 Copyright Holger Willrath 2011

3 Contents Page I Contents 1 New Features and Changes Context Training Course 1 2 Simulation Engines 1 3 Underfloor space Ventilation Insulation of the walls of the under floor space 4 4 Wall to Roof Space Heat Transfer 5 5 Modelling Roof Space above Outside Air 6 6 Elevation and Ventilation 7 7 Polystyrene/Sheet Steel Sandwich Panels Internal and External Walls Ceiling/Roof 7 8 Batch Processing Location Orientation 9 9 Mirror Reversed Plan Example Single Storey - Elevated Floor Perspective Drawings Plan and Roofline Elevations Internal space Description of the house Zoning 16 List of Figures Figure 1 North West corner Figure 2 North East corner Figure 3 South East corner Figure 4 South West corner Figure 5 Floor plan Figure 6 Roofline Figure 7 North elevation Figure 8 East elevation Figure 9 South elevation Figure 10 West elevation Figure 11 Section through formed ceiling space Figure 12 Section through raked ceiling Figure 13 Section through the different roof spaces Figure 14 Cut away of the house Figure 15 Zoning of the house List of Tables Table 1 Description of building elements... 16

4 BERS Pro Plus4.2 New Features and Modelling Changes Page 1 1 New Features and Changes 1.1 Context As a result of an exhaustive NatHERS accreditation process a number new capabilities have been introduced into the BERS software. Additionally a number of changes have been introduced to various algorithms used within BERS to make them exactly the same as the algorithms used in ACCURATE. These changes have been made to get closer results from the two software packages in order to make the administration of the NatHERS Scheme easier rather than to add accuracy to the simulation process. A number of other features have been added as part of Solar Logic s ongoing development process. These include the batch processing for various combinations of locations and building orientation, the ability to mirror image plans, and the inclusion of polystyrene/steel sandwich panel for roof/ceilings and walls. 1.2 Training Course This one day training course has been designed to be part of Solar Logic s ongoing program of providing continued professional development to building energy assessors. It provides the skills required for the correct use of the new features introduced into BERS Pro Plus Version Simulation Engines BERS Pro V contains 3 simulation engines. CHENATH V2.13 is the NatHERS approved engine which contains a programming bug. CHENATH V2.20 has the bug fixed. CHENATH V2.23 also has the bug fixed but should only be used for non star rating CO2 emission calculations because it uses the internal heat gains due to appliances defined by the assessor. BERS Pro V4.2 defaults to the NatHERS Regulatory mode when first opened. When BERS Pro V is used in NatHERS regulatory mode a NatHERS compliant Certificate can be printed and issued. NatHERS regulatory mode means using the NatHERS approved CHENATH V 2.13 thermal simulation engine which was released several years ago. In this mode a NatHERS certificate will be produced but CHENATH V 2.13 will have been used during simulation.

5 BERS Pro Plus4.2 New Features and Modelling Changes Page 2 There is a software bug in CHENATH V 2.13 that affects the ability of the software to assess open plan buildings correctly because of the way ventilation is modelled. The NatHERS administrator is aware of this issue and will approve the release of a new version of the CHENATH engine that fixes this problem in the near future, probably around the end of the 2011 or the beginning of This new engine will then become the NatHERS accredited simulation engine. CHENATH V 2.20 is an updated version of CHENATH V2.13 that allows the better ventilation modelling required for open plan dwellings. If BERS Pro V is used in non regulatory mode then CHENATH V 2.20 can be substituted for the flawed CHENATH V2.13 engine. Although this engine is not NatHERS approved it has a better ventilation algorithm and is therefore better for assessing dwellings that use ventilation as a major thermal control strategy, ie it is better for evaluating buildings in Queensland and other warm locations. When using CHENATH V 2.20 a NatHERS certificate cannot be produced. If BERS Simulation is selected as the simulation mode then CHENATH V2.20 can be selected. After simulation this will produce a BERS Certificate that is based on using CHENATH V2.20.

6 BERS Pro Plus4.2 New Features and Modelling Changes Page 3 Assessors in Queensland are advised to get the appropriate training and switch over to BERS Pro V They should continue using CHENATH V2.20 until such time that the NatHERS administrator accredits the use of a CHENATH engine that incorporates the better ventilation model. 3 Underfloor space 3.1 Ventilation Different degrees of underfloor ventilation affect the rate of heat transfer through the floor to the air below and then out of the underfloor space. Totally open should be selected when the floor is high above the ground and there is very little to impede air movement under the floor. The modelling assumes outside air temperature under the floor. High set houses and upper floors of houses that protrude beyond the floor should use this option. Very open and open assume little in the way of sides but require knowledge of height above ground. Very open would be used for a floor with an average height of 1.2 metres or less above the ground with no sides at all. Open is used where 1 or 2 sides are enclosed.

7 BERS Pro Plus4.2 New Features and Modelling Changes Page 4 Enclosed requires the wall material and insulation level to be identified as well as the ventilation area. All sides must be enclosed with only small openings provided to maintain dry conditions under the house. The area of these openings must be entered. 3.2 Insulation of the walls of the under floor space Even though the practice of insulating the walls of the under floor space is rare it can be shown that in some climates it is worth doing. This feature allows different materials and levels of insulation to be modelled.

8 BERS Pro Plus4.2 New Features and Modelling Changes Page 5 4 Wall to Roof Space Heat Transfer If a room with a cathedral ceiling is next to a room with a flat ceiling and roof space the wall next to the roof space is often not insulated. While this is poor practice the insulation is often omitted and this feature allows the energy costs of omission to be evaluated. In cases where the wall between the zone and the roof space is fully insulated the ceiling area should be increased by changing the tilt of the ceiling until the area matches the sum of the ceiling area plus wall area. A coffer ceiling is example where there is additional vertical wall area in contact with the roof space where ideally the wall should be insulated to the same level as the ceiling. The diagrams below show how the additional area of 9.5 m² of vertical wall should be modelled. The first data entry method would be used if the vertical walls are insulated the same level as the ceiling. The second method should be used if the walls of the coffer ceiling are uninsulated.

9 BERS Pro Plus4.2 New Features and Modelling Changes Page 6 Some roof spaces may include a loft area that can be modelled as a zone on a second or third level. In this case the walls adjacent to the roof space are modelled as being external wall that have an additional amount of insulation equivalent to the R value of the roof insulation. 5 Modelling Roof Space above Outside Air In general the surface area of a roof space should be kept to a minimum to reduce heat ingress during cool periods and heat loss when it is cold outside. If a roof is extended over an open area such as a deck or carport then there should be a barrier within the roof space to separate the space above the zoned part of the house and the space above the open area. This feature allows the modelling of bad practice in the case where no separation barrier is provided. The example below shows the roof cavity extending over 40m² of unenclosed (unzoned) verandah area.

10 BERS Pro Plus4.2 New Features and Modelling Changes Page 7 6 Elevation and Ventilation Within the height range of modern buildings the wind speed increases with altitude. The CHENATH engine calculates this from the height of the floor of the lower storey above the ground. 7 Polystyrene/Sheet Steel Sandwich Panels 7.1 Internal and External Walls InsulWall panel consist of an expanded polystyrene core encased in sheet steel. The thickness of the EPS section defaults to 140 mm for external walls and 125 mm for internal walls but these thicknesses can be readily changed. 7.2 Ceiling/Roof SolarSpan consist of an expanded polystyrene core encased in flat sheet steel on the ceiling underside with a profiled steel sheet on the roof side. The thickness of the SolarSpan cannot be changed in the software and remains 125 mm. Insulation can be added however to emulate EPS thicknesses greater than 125 mm.

11 BERS Pro Plus4.2 New Features and Modelling Changes Page 8 Care must be taken not to account twice for the EPS. When choosing the roof the steel outer option without insulation should be selected. When choosing the ceiling type select the SolarSpan option which models the steel ceiling sheet plus the EPS. The Steel Outer of SolarSpan should be selected as the roof. Since the SolarSpan contains no air gap, No added insulation, no air gap should be selected for the insulation option. The Unvented, no cavity Roofspace Ventilation option should also be selected. Selecting Roof, No Cavity in the ceiling option window will automatically result in Unvented, no cavity displayed in the roof option window.

12 BERS Pro Plus4.2 New Features and Modelling Changes Page 9 8 Batch Processing 8.1 Location The batch processing mode makes it possible to run the simulation for any or all of the 69 locations for which climatic data is available. The climate file is selected by ticking the box next to it. Different post codes can be entered for each location. This changes both the latitude and longitude and slightly different simulation results will be generated than for the named location. The set of locations for batch simulations can be saved and reused. The batch results can be printed out or copied and pasted into a spreadsheet for further analysis. 8.2 Orientation The plan can be simulated for the original orientation or each location selected can be oriented in each of the 4 cardinal orientations or for each of the 8 cardinal plus cross cardinal orientations.

13 BERS Pro Plus4.2 New Features and Modelling Changes Page 10 9 Mirror Reversed Plan A mirror image of the plan can be constructed using the Mirror button. The plan in the background is removed when this is done. The modelling of sun obstruction is not mirrored but stays the way it was modelled for the original plan. It is probably best to eliminate any sun obstructions when comparing the thermal simulation results of mirror reversed plans.

14 BERS Pro Plus4.2 New Features and Modelling Changes Page Example Single Storey - Elevated Floor 10.1 Perspective Drawings Figure 1 North West corner Figure 2 North East corner Figure 3 South East corner

15 BERS Pro Plus4.2 New Features and Modelling Changes Page 12 Figure 4 South West corner 10.2 Plan and Roofline Figure 5 Floor plan

16 BERS Pro Plus4.2 New Features and Modelling Changes Page 13 Figure 6 Roofline 10.3 Elevations Figure 7 North elevation Figure 8 East elevation

17 BERS Pro Plus4.2 New Features and Modelling Changes Page 14 Figure 9 South elevation Figure 10 West elevation 10.4 Internal space Figure 11 Section through formed ceiling space

18 BERS Pro Plus4.2 New Features and Modelling Changes Page 15 Figure 12 Section through raked ceiling Figure 13 Section through the different roof spaces Figure 14 Cut away of the house

19 BERS Pro Plus4.2 New Features and Modelling Changes Page Description of the house Element External Walls Internal Walls Floors Ceiling Roof Eaves External Hinged Doors Sliding Door Internal Hinged Doors Windows Description Brick veneer, dark colour. R1.5 plus antiglare foil insulation. Plasterboard lined stud wall, heights refer drawings Elevated timber 1200 mm above ground, floor coverings as per drawings Flat plasterboard R3.0 insulation Raked mm SolarSpan Hip, gable, 22.5 slope, dark colour Iron roof anti glare foil above flat ceiling SolarSpan one piece ceiling/roof Refer drawings Solid core, refer drawings. See drawings. Single glazed clear, aluminium frame Hollow core, refer drawings Clear single glazed aluminium frame. Refer drawings. Table 1 Description of building elements 10.6 Zoning Figure 15 Zoning of the house