An Energetic Profile for Existing Office Buildings

Standards for sustainable design and energy efficiency in buildings are continuously being developed under the title of “Green Building” in Israel and abroad. However, a large number of existing buildings were not built in accordance with these green principles. In the US new “Green Buildings” are growing at a rate of 20% per year, but new construction accounts for only 2% of existing buildings. In addition, there is a wide range of results measured for energetic function of buildings that were systematically evaluated by green rating systems, such as LEED.

The term “Profile” is often used in different disciplines to identify the fundamental properties of an object, while analyzing future steps to use them: companies and corporations use Business Profile for firms or products to assess their assimilation into the market, employment agencies use Personality Profile to identify the qualifications of a candidate for a job, and there is even a Constructive Profile for testing a structure’s resistance to earthquakes.

The motivation for this research is to create an Energetic Profile, inspired by a simple blood test indentifying the inner condition of a person, compared to the general population and to his/ her own previous and future tests. In the same way, the aim of the Energetic Profile is to define the energetic potential of an existing building, compared to other buildings and to itself.

In this research, the features of Energetic Profile for Existing Office Buildings were developed. The Energetic Profile consists of seven architectural parameters, assembling the “DNA” of the building. The parameters are geometric and fundamental in nature, simulating the building in its construction stage, before finishing materials and building systems are added. The suggested profile scans the building from macro to micro, analyzing the influence of its nearest surrounding environment, the building morphological characteristics up to the plan of the typical floor.

The seven parameters comprising the Energetic Profile are: (1) Building’s environment (2) Building’s envelope (3) Compactness (4) Form factor (5) Flexibility (6) Floor efficiency (7) Space type division.

The Energetic Profile enables the analysis of energy saving opportunities for different office buildings, identifying its unique characteristics. In addition, the profile enables distinction between energetic- architectural typologies of office buildings which are not commonly discussed in green standards and rating systems.

For each of the parameters a methodology was developed to investigate the impact of the parameter on the total energy consumption (divided into cooling, heating and lighting) in a theoretical office building located in a hot and humid climate typical of Tel- Aviv. Simulations to calculate the energy consumption in each case were performed using ENERGYui interface, based on the energy simulation program EnergyPlus.

The use of the Energetic Profile for Existing Office Buildings was examined through case studies which demonstrate the effectiveness of the tool to identify potential action directions for energy savings for an existing office building, compare design alternatives, and examine the influence of various construction phases of the building. Future contribution is displayed as an auxiliary tool for planning new office buildings.

The aim of this study is to create an Energetic Profile identifying potential energy savings in existing office buildings. The main objectives are:

1. Identifying the “DNA” of the building in accordance with its energetic, geometric and functional characteristics.

2. Evaluating the hidden potential of energy efficiency in office buildings while using a fast, non simulated method, which is appropriate for use in many existing buildings.

3. Creating a scale of values pointing on failures and opportunities for energy savings in the building.

4. Developing a tool that can be implemented on any office building while keeping its unique characteristics and typology.

A comprehensive literature review allocated different parameters influencing the energy consumption of an office building to groups such as geometric -non geometric, primary -detailed, large scale -small scale, functional -architectural and long term -short term effect on the building’s life cycle. From these groups seven parameters were selected. These are:

1. Environment
2. Envelope
3. Compactness
4. Shape Factor
5. Flexibility
6. Floor Efficiency
7. Space Type Division

Each of the parameters has been tested independently. As part of the methodology, new indicators were developed in places where the ones found in the literature were not sufficient. The analysis of each parameter consists of four parts: (1) Introduction – of literature review and major studies, (2) Methodology- creating a set of tests using ENERGYui, (3) Results and conclusions – comparing the different cases in each parameter according to the energy consumption in a theoretical building divided into cooling, heating, lighting and total energy consumption, and (4) sensitivity analysis if needed. The base case used in this study is a theoretical model of a typical 5 story office building, 1210 m2 per floor, length to width ratio 2:1 tested North- South orientation and East- West orientation, in Tel- Aviv city’s climate. The building was modeled in ENERGYui interface which serves the Israeli Standard 5282 for Energy Rating of buildings. The Base Case was designed according to Israel’s planning laws and standards.

The conclusions of each parameter were integrated into the Energetic Profile creating a scale of values in each one of them. The Energetic Profile was then divided into two parts (Figure 1):

(1) Design Energetic Potential of the building representing the savings potential of the building compared to the maximum energetic potential line of the profile, representing the minimum energetic consumption found in each parameter.

(2) Actual Achievable Energetic Potential of the building which is derived from the building’s “As Is” function, and considering constraints which may prevent changes in the building.

The first part allows comparison of the designed building to other buildings as they all measured against the minimum consumption line of the profile, and identifying the opportunities for energy savings. Each building has its own unique profile based on its specific characteristics and flexibility for changes. The second part enables determination of the actual achievable savings in the building based on its own geometric, constructive and functional constraints.

The Energetic Profile for Existing Office Buildings proposed in this study enables the identification of strengths and weaknesses of energetic potential in different office buildings according to their location, design and function.

The profile is a tool to compare different buildings not only to others, but also to themselves: from their current status to their achievable improvement. The profile is suitable for use in a primary stage of investigation pre intervention in existing buildings. The case studies presented in this work proved up to 50% in savings potential compared to current condition, when implementing the conclusions of the profile.

Though the profile was developed for existing buildings, it can also add a significant value at the different design stages of new building by utilizing the results regarding energy savings in each parameter.

Furthermore, although the focus of the profile was to reduce the total level of energy consumption of the building, much emphasis was placed on the subject of natural daylight. Natural light does not only serve as a major contributor for energy savings, but it also holds benefits for the quality of the building’s interiors and human activity.

A further research could extend the conclusions found in this work to other climate zones and building types, as well as developing the Profile as a design tool for new construction.