Research Systematically Approach

The main aspect of this research methodology concerns the three phases of the project that are required to be conducted in order to answer the research questions and achieve the aims and objectives (Figure 4.4). Each phase of this research is an important requirement before moving on to the next phase of the study.

Creating the base-case concept and calibrating the simulation software is the first phase of this research. The second phase is to propose an optimised case through a parametric analysis of building designs and elements which are conventionally practiced in the country. This includes both the conditioned and unconditioned (free running) modes of buildings. During the third phase the base case is further optimised by applying additional measures. The following sections present each phase in detail.

82 Base case concept (base

on Heating and cooling set points)

Building free running evaluation based on the

conventional building elements and design(applying thermal

comfort range)

Building free running evaluation as a result of

initiative construction methods

Energy evaluation based on applying conventional building elements and

designs

Energy evaluation based on applying initiative construction methods to reduce both heating and cooling energy consumption

Optimised case(1), based on the most efficient selective parameters mixed with free running

building

Optimised case (2), based on the most efficient selective parameters mixed with

free running buildings

Base-case

Calibration and validation Free running building evaluation Building energy consumption evaluation Phase 1 Phase 2 Phase 3

Figure 4.4 – Research Approach Overview

Phase 1

It is important to calibrate and validate the performance of the base case by employing simulation software. For this purpose, the building’s drawings and energy bills were provided for simulation and comparison. However, as mentioned previously, the setting points of the occupant activities for controlling the temperature, and occupancy schedules are unknown. To solve this problem, the Iranian housing census presents the average building occupancy and other information and these were applied to the simulation software. The results of the

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simulation were then compared to the actual building energy bills of the same case, and other similar cases.

Figure 4.5 shows the actual and statistical details of the buildings. It is assumed that the combination of these parameters will reflect the approximate energy performance of the building.

The last step of this phase is to apply the set point temperature that is not applied in the base case, however, the new Iranian building code (chapter 19) requires that new residential buildings have temperature set points and these will be the reference case for the next phase of this research.

Phase 1 Base Case

Actual parameters

 Heating and cooling

systems

 Energy bills

 Building drawings and

construction details

 Building orientation

Parameters based on national census literature reviews

 Occupancy size

 Occupancy time

 Heating and cooling

operation time

 Heat gains

 ACH

 Temperature set points

Calibrated base case

Base case concept After applying Temperature set points of national

building code

Figure 4.5 – Phase One Flowchart

Phase 2

This section defines how different building fabrics perform, under the same conditions, with respect to thermal comfort and energy consumption performance.

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For this section the existing building elements such as wall types, window sizes and types, and different ventilation time plans and controls will be evaluated systematically to a) determine the best element and performance, and b) determine the best case as a result of combination of the evaluated building elements and strategies.

The model and assumptions are kept the same for all the simulations. The only changes are when the building elements and strategies are replaced in turn systematically.

A parallel analysis will be carried out to evaluate the building performance in unconditioned mode, the selected best performance building fabric and designs will then be coupled to the findings of the best energy performance case to create a mixed building design.

Consequently, the base case simulations as a result of each element are then compared to the base case and the best performance is picked to shape the Phase 2 case (Figure 4.6).

Phase 2 Base-case concept Variable parameters  Wall types  Window types  Window sizes  Natural ventilation time plans

 Natural ventilation inlet sizes

Constant parameters

 Floor type

 Partition walls

 ACH (infiltration rate)

 Internal heat gains

 Occupancy time scheduale Energy consumption evaluation Free running evaluation Optimised case (1)

Figure 4.6 – Phase Two Flowcharts Phase 3

The constant parameters in phase 3 are identical to the previous phase, however, the variable parameters are modified for two main reasons; a) to optimise the heating energy consumption,

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and b) to optimise the cooling energy consumption. For the first objective, insulation materials with the same details are applied to the wall types. For the second objective, different strategies for solar control through the windows are applied to the building.

The suggested strategies and methods will also be evaluated in unconditioned mode to identify the most efficient building fabric and design for free running buildings.

Eventually, the combination from both evaluations will be examined to suggest the best performance case (Figure 4.7)

Phase 3

Optimised case 1

Variable parameters

 Wall types with insulation materials

 Fixed and removable Overhangs

Constant parameters  Floor type

 Partition walls

 ACH (infiltration rate)

 Internal heat gains

 Occupancy time scheduale Energy consumption evaluation Free running evaluation Optimised case (2)

Figure 4.7 – Phase Three Flowcharts

Making multiple design decisions simultaneously is a large challenge for designers when designing for low energy buildings. This is a complicated process to select the best parameters for multiple sub-systems, and predicting this choice will represent the best integrated system. In reality, each parameter integrates with others and impacts on the overall performance. For instance, an efficient glazing system in a passive design needs to be integrated to the other strategies to be optimized. This includes the amount of thermal mass

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and insulation, solar gain control and space heating controls.

Therefore, in this study, depending on the parameters frequency, parametric or sensitivity analyses are considered.

The limitations of these methods have been identified and have been addressed during the analysis. For example, during a parametric analysis an analysis might be performed on a parameter, during which the other parameters are set to values that do not allow it to be properly characterized. A compelling example is the level of thermal insulation of walls, while the material with higher thermal mass performs better than the others, once they are integrated with natural ventilation during summer time, the performance changed conversely.

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Chapter 5 – Development of Base