Reference no: EM132414564 , Length: 22 Pages

KB7003 Building Energy And Environmental Modelling Assignment - Northumbria University, UK

Learning outcomes tested in this assessment -

1. Select and defend an appropriate method for modelling a given energy system.

2. Explain the limitations and weaknesses of the method used.

3. Successfully design, build and use a simulation model describing the dynamic response of an energy system.

4. Critically evaluate and explain the results obtained from a dynamic simulation model of an energy system.

5. Explain the benefits and limitations of dynamic simulation modelling compared with conventional professional design practice.

Part A: Building Energy Modelling

Assignment Brief: This assignment is designed to enable you to develop skills in the modelling of a building using dynamic thermal modelling software and to generate and interpret results describing internal comfort and energy balances and their relationships with climate data and thermal insulation standards. You are required to submit a typed report setting out the modelling objectives, defining all input data, identifying all modelling assumptions, presenting the results to the tasks specified in the attached, describing and analysing the results, and drawing conclusions which address the report objectives. Please see detailed instructions at the end of this document.

TASK 1 - freefloat

Develop your building model making choices of construction materials which just meet the requirements of the 2010 Part L Building Regulations. Make (and state) reasonable assumptions regarding allowances for occupancy, lighting, casual heat gains, infiltration and fresh air ventilation allowances and the usage schedules attached to these variables. For all of these considerations, you are encouraged to use the in-built databases in DesignBuilder where practicable.

When your model is complete, simulate the freefloat internal temperatures and extract and present results for ONE key space (of your choice). The freefloat temperatures are those that would exist in the presence of normal building usage but without any plant (heating or cooling) inputs whatsoever. The temperatures you extract should be the operative results. Select a suitable peak summer and winter week as a basis for your results presentation. Generate a first set of results for this task using the 'control' weather file and a second set using the future weather data. Plot the results for both weather files on the same graph axes for a direct comparison.

TASK 2 - heating and summer comfort

Now 'switch' heating plant on. Apply (and state) suitable choices of winter heating set point in all relevant spaces together with appropriate and fully-defined heating plant settings. Impose a 3 air change per hour scheduled natural ventilation rate to come on during warm summer months when the internal temperatures are above the heating set points. Re-run your model using both weather files and extract heating plant profiles for your winter sample week, together with freefloat operative temperatures during the summer week. Go on to extract the annualised total energy usage due to heating plant.

TASK 3 - cooling

Now 'switch' cooling plant on taking care to re-set your natural ventilation profiles so that only constant minimum fresh air allowances are applicable during occupied hours. Apply (and state) suitable choices of summer cooling set point in all relevant spaces together with appropriate and fully-defined cooling plant settings. Re-run your model using both weather files and extract cooling plant profiles for your summer sample week. Go on to extract the annualised total energy usage due to cooling plant.

Task 4 - implementation of changes

For this task please use and apply an appropriate heating and cooling system to the building. From your knowledge and analysis of the previous 3 tasks propose and apply two changes to the building to reduce its overall energy consumption in the future. Provide reasoning and argument of why you are making these particular changes. Initially analyse each of these changes in isolation to each other and then analyse the effects of the combination of these two changes on future building energy use. Use appropriate references to support your arguments.

Analysis and Discussion - Present your results in a clear and appropriately labelled graphical method. Demonstrate what you understand and what you have learned from the results (though take care to use an authoritative 3rd person past-tense format as if it were a professional report). Focus on the implications of a changing climate on design decisions taken today for new building proposals. Remember that many buildings planned for construction or refurbishment today might be expected to still be in use in 2080. What practical advice can be given to designers, constructors and building users to respond to the challenges likely to arise from evolving improvements to construction standards and a changing climate?

Part B: Ventilation Modelling Using CFD

Assignment Brief: This assignment is designed to enable you to explore in some depth the use of Computational Fluid Dynamics (CFD) to analyse the air movement and temperature distribution within a simple room under a range of different scenarios. Please produce a professionally presented academic report detailing your critical analysis of each of the five cases set out within this brief.

You are to use the PHEONICS CFD software available in all the Mechanical and Construction Engineering IT Laboratories for this assignment. This software will be demonstrated in the IT lab sessions and there is a set of four self-study tutorials available on the module eLP site which will be helpful in building your CFD skills and understanding. Please be aware that it takes time to build confidence with CFD software and that in order to maximise your learning potential you need to engage fully right from the early sessions and to dedicate significant additional time outside of class. You can then bring your questions along to the next class to discuss with the tutor to build your confidence and skills and doing so will prepare you will to answer this assignment.

Introduction and Geometric data: Five variants (A-E) of a simple case are presented below to allow you to simulate air and temperature distribution in a single rectangular room using CFD modelling. Two isothermal cases A and B focus on the air distribution in the room whilst cases C, D and E concentrate on the natural and mixed convection heat transfer in the room.

Key dimensions:

Room size: 5.2m (L) x 3.6m (W) x 2.7m (H)

Supply grille size: 0.4m (W) x 0.15m (H)

Extract grilles size: 0.2m (W) x 0.2m (H)

Furniture size: 1.8m (L) x 1m (W) x 0.8m (H)

Window size: 3.2m (W) x 1.5m (H)

Radiator size: 2.0m (W) x 1.0m (H) x 0.05m (D)

In cases A, B & D, a supply grille is positioned at the centre of the west-facing wall, at a distance of 0.2m from the ceiling to the top edge of the diffuser. The discharge angle of the diffuser is horizontal. There are two extract grilles located in the two corners of the east wall, with a distance of 0.2m from the edges.

In cases C & D, there is a sash window located in the south-facing wall, at a distance of 0.8m above the floor. In case C, a single panel radiator is added to the room, which is located 0.1m in front of the south-facing wall and 0.1m above the floor.

Present and discuss the CFD results and include the key settings information such as the size of cells, the number of grids in each dimension, and the number of the iteration simulated. For cases A and B you need only present graphics of room air velocity. For cases C and D you should present graphics of both room air velocity and temperature. Discuss your results in the context of satisfactory room air distribution (cases A and B) and room air distribution and thermal comfort by using air distribution performance index (cases C, D and E).

Attachment:- Building Energy And Environmental Modelling Assignment File.rar