PAZO DE VISTA ALEGRE.

Two key research components for analysing energy efficiency in residential building are conducted in this PhD research: one is to tap the technical potential of building construc- tion and energy equipment, another is to investigate the impacts of diverse occupant be- haviour on residential energy efficiency. The former is supposed to be developed based on Retro-commissioning (RCx) and International Performance Measurement and Verifi- cation (IPMVP). The latter is the energy-related occupant behaviour, which is considered as one of six influencing factors of building energy performance, i.e. climate, building construction characteristics (e.g., type, area, orientation, material etc.), building energy service and equipment, operation and maintenance, occupancy rate and occupant behav- iour, and indoor environmental conditions and requirement (Yu et al. 2011). The ontology

of DNAS mentioned before works as the conceptual framework for analysis of occupant behaviour and occupancy rate. Data collection is performed by the way of surveying elab- orated in section 4.1, which provides the factual basis for discussion following the guide- line of DNAS.

Based on common RCx and IPMVP, as well as DNAS ontology, an integrated-RCx (In- tRCx) concept is proposed to composite the technological factors and human factors that influence residential energy efficiency. This integrated concept aims to introduce an up- dated standardization, which could serve as a synthesized method or portfolio for energy efficiency analysis of residential building.

4.2.1 Retro-commissioning (RCx)

Retro-commissioning (RCx), also be called Existing Building Commissioning (EBCx) is “…a systematic process for investigating, analyzing, and optimizing the performance of

building systems through the identification and implementation of low/no cost and capital intensive facility improvement measures and ensuring their continued performance.”

(Marlow 2014, p.7). Retro-commissioning is a method to find out and address deficien- cies and risks that affect the residential building’s energy performance and living comfort. As a systematic method RCx is distinct from the other two concepts: Building Commis- sioning and Re-commissioning.

- Building commissioning, is a verifying process in new buildings, depending on project scope, some of subsystems (e.g., systems for mechanical, plumbing, elec- trical, fire/life safety, building envelopes, interior systems, sustainable systems and building security system etc.) that need to be verified to achieve owner’s pro- ject requirements (OPR) as intended by the building owner and as designed by the building architects and engineers. Building commissioning describes a quality management process that ensures all energy-related systems of building to be de- signed, installed and operated for an optimal performance. As considered, build- ing commissioning gives a final check of all or some necessary systems, involving to a more progressive process that includes not only systematic verification and testing, but also staff training and thorough documentation of all systems.115 - Recommissioning, can be understood simply as a methodical process of testing

and adjusting all or some of the aforementioned subsystems in building commis- sioning. It can take place any time after a building is operated fully. The decision to recommissioning might be triggered by a change in building use or ownership, the onset of operational problems, or some other need. (Haasl and Heinemeier 2006).

Retro-commissioning can be understood as another form of recommissioning to some extent, but the building usually has been used longer and have never been commissioned before. RCx relies on building and energy-related equipment documentation, along with functional testing to optimize performance. Four distinct phases generalize the process of RCx briefly: Planning, Investigation, Implementation, and Hand-Off, as Fig. 4.2 illus- trated (Haasl and Heinemeier 2006). RCx for enhancing energy efficiency of existing building can take place at any time, unless the facility and/or major equipment are pro- grammed for replacement in the immediate future (DOE 2014).

Figure 4.2 Four phases of Retro-commissioning (RCx) processes (Haasl and

Heinemeier 2006)

Building is normally designed and constructed reliably and efficiently as far as possible, and expected to be used and operated as efficiently as architects and engineers expected. However, in reality, the building systems may have more or less “wear and tear” and become increasingly unreliable and inefficient owing to incorrect utilization by occupants who cling to their habits and thoughts, as well as lack of regular maintenance by well-

trained staffs, or outdated technologies and environmental changes.

Most existing residential buildings in Germany that were built a few decades and before had never undergone a formal and comprehensive commissioning process, even those recently built adhering to some building energy efficiency criteria have not systematical quality assurance services like RCx. Many problems or risks would be analyzed and re- solved only after they appeared and caused trouble to daily life of occupants. In particular, social housing occupied normally by people with low income or relative low educational background, which determines that RCx may be more necessary for this building group, if a cost-effective approach is preferred to, because RCx is a results-oriented and com- prehensive approach instead of mere „System check-off and restart”. The Retro-commis- sioning process and tools has to be performed within the enclosed timeline. A concrete work process of RCx based on past projects includes the steps described in Fig. 4.3 (Kat- zenbach et al. 2015).

*”Retrocommissioning Handbook for Facility Managers” 2001.

Figure 4.3 General workflow of RCx considering occupant behaviour

4.2.2 International Performance Measurement and Verification Protocol

International Performance Measurement and Verification Protocol (IPMVP) is used to assess the results of energy saving investments and measures. It is commonly applied in industry or buildings with large-scale systems, thus it is has to be adjusted or simplified