Step 1: Selection of the case study office buildings

Chapter 2 section 2.11.3 presented the key selection criteria for the case study office buildings, ie, building design and location. These criteria were then expanded with performance influential parameters showing the impact that they can have on the environmental performance of the HVAC and on the way systems are used by the occupants, depending on occupancy patterns. These criteria have been further expanded as they emerged through the need to justify further the selection criteria. The added criteria have been selected considering the research gaps of the literature review and the problem statement in chapter 1.

This section presents the criteria categorised by their level of importance to enhance case study comparison and to address the goal and scope definition of the study and its further system boundaries. These criteria have been described in chapter 6 as case study building characteristics and in a MATRIX table provided in appendices (see more in section 4.3). The level of importance for the selection is presented in table 4.3:

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Table 4.2: Case study selection criteria Level of

importance

Selection criteria What to look for

Primary BREEAM excellent (certified before 2009)

The first important selection criteria are to choose BREEAM excellent certified office certified before 2009.

Primary Building age -life span

Building age is a significant criterion for selecting both BREEAM offices and conventional offices:

1. New BREEAM excellent offices to be built after 2008 and fully operated since 2009.

2. Existing old office buildings that were built after 1950s and had no building refurbishments.

3. Existing old office buildings that were built after 1950s and had an upgrade in their heating system to represent these types of buildings.

4. Existing old office buildings that have reached 50 years of age.

The case study offices must be of:

1. Different architectural styles 2. Similar size in total m² 3. Similar building shape

4. BREEAM offices west orientation

5. Conventional offices north or south orientation Primary Location

-temperature -heating Degree Data

-surroundings

1. For every case study, it is important to consider that the case study buildings are located in the same country and possibly in the same town/city within close distance.

2. The case study building must represent different regions in the UK in order to consider different local temperatures from North to South and to Midlands.

Also the Heating Degree base temperatures must be different.

3. The surroundings can have a great significance in the environmental performance of the buildings so buildings that are located in open areas are preferable.

Primary Building

occupancy (BO)

1. BREEAM office buildings to be fully occupied (ie, all floors are occupied)

2. Conventional buildings that are fully occupied 3. Conventional buildings not fully occupied to represent a large number of existing office buildings in the UK, were major decisions need to be taken about demolition or renovation.

121 Level of

importance

Selection criteria What to look for

Secondary Heating/cooling technology -energy efficiency -conventional

1. BREEAM office should have low-energy claimed heating/cooling systems types with passive

cooling/heating. Natural gas condensing boilers with heat recovery and with local power generation such as CHP are needed for the study.

2.Conventional central heating low-energy efficient boilers

Secondary EPC 1. Energy performance certification of B’ on BREEAM excellent offices.

2. Energy performance certification of B’ or worse for conventional office buildings.

This is important to show that both a sustainable and a conventional office building can have the same EPC score (section 2.3.1, Nunes at al 2013 study).

Secondary Representable benchmarks

The ECG 19 benchmarks are not up to date, although the criteria for the selection of the conventional office buildings is Type 3-Typical Practice and for the BREEAM offices Type 3 better than Good Practice in these benchmarks.

Secondary -Building Construction -Building Fabric

1. The BREEAM offices must be of different construction materials to represent different building materials from different regions (brick, stone, pre-cast concrete).

2. The BREEAM offices must be fully insulated.

3. BREEAM offices must be double-glazed.

4. The conventional office buildings must be representative of 1950s onwards so pre-cast concrete is an ideal construction material.

5. Conventional offices must be non-insulated and single-glazed.

Secondary Ownership 1. One case study to be public buildings/

government owned (some reductions in CO₂ have appeared, refer to introduction 3000 central government buildings).

2. Another case study to be privately owned.

Source: Own interpretation

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The above selection criteria according to the level of importance depended on building selection process explained in the following section.

Sample: Case study selection process and constraints

Based on the above selection criteria and the level of importance, the identification of possible office buildings for the study started by searching BREEAM ‘excellent’ certified office buildings through the BREEAM’s website under the office buildings case studies.

Several case studies were found. The first two buildings that met the BREEAM criteria were the new office building called ‘Palestra’, located in London and the refurbished office buildings called ‘100 Hagley Road’ in Birmingham. Access to the Palestra building was denied due to major publicity of its BREEAM case mentioned in the Introduction, chapter 1. Access on Hagley Road was provided and after the first site visit, requesting explicit data on energy consumption, access was denied.

A paper presentation of this study by Dimitrokali (2009), at the ‘Central Europe towards Sustainable Building’ conference in Prague was useful in identifying Bennetts Associate architects, having presenting their large portfolios of BREEAM certified buildings. This was a successful contact and two BREEAM office buildings were finally selected and these are:

1. Potterrow: BREEAM ‘excellent’ certified new office building, built in 2008 with CHP technology for heating and cooling, located in Edinburgh.

2. Elizabeth Courts II (EIIC): A BREEAM ‘excellent’ refurbished office building built from 2008, with energy-efficient claimed technology for heating and cooling, located in Winchester.

The selection of these two cases set the specific detail criteria for selecting the conventional office buildings. So the conventional office buildings, one in Edinburgh and one in Winchester, had to be of similar size as the pair BREEAM of office buildings in the same locations.

Desktop research through development and investment companies did not help to find the right match. The next thought was to look at project collaboration between the University of Central Lancashire and the School of Built and Natural Environment.

Through this collaboration a building development company was identified that had a large portfolio of conventional office buildings, although the name of the company cannot be mentioned following a confidentiality agreement. The selection criteria for the comparison analysis, size and location were filtered in a database. A match for the case study in Edinburgh was found, which is:

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1. Argyle House: A conventional existing office building dated from 1950s-1960s