Refurbishment or Replacement of Buildings – What is Best for the Climate?

Introduction

In 2008, the Norwegian Bank “SpareBank 1 SMN” decided to reestablish their headquarters in Trondheim, Norway.  The old facilities were considered to be increasingly inadequate, not very functional or usable with respect to changes in the performance of bank services today and in the future. The existing headquarter building was from the early 70s. 

The challenge was to decide whether they should rehabilitate the existing building or demolish it and construct a new building.  The project presented in the paper addresses this issue. The paper shows the usefulness of life cycle models as input to a decision making process in a feasibility phase of the project.

 

Methodology

Several studies have used life cycle assessments to measure the impacts of energy consumption in different building stocks in a quantitative way (UNEP, 2007).  But as an input to decision making for building owners or contractors evaluations of environmental performance of buildings, these studies have often been less helpful, as they to a great extent have been limited to the environmental impacts associated with the manufacture of building materials. The experience of both producers and contracting authorities has been that decisions are taken on the basis of insufficient information with regard to environment and economics in a life cycle perspective.

The methodology used is a merge of the Life Cycle Costing methodology - LCC and Life Cycle Assessment – LCA (Rønning et al., 2007). Calculation of the environmental profile for the whole building was based upon data from databases, NAMEA statistics, general LCA software and the Norwegian LCC-standard.

The comparison is based on calculation of greenhouse gases related to the phases Building construction (cradle to gate for building materials and components), Operation, Maintenance and Development during the life span of 60 years of the two alternatives.  Demolition - or End of Life – was not included in the comparison, but is included in the general model.

The total energy demand for the existing building is relatively high, 524 kWh/m².  The goal for the new or refurbished construction was a net energy demand on 85 kWh/m².  The existing construction is considered to have low adaptability and area effectiveness.  Thus, the comparison must take into consideration a relatively extensive refurbishment including upgrading of the existing building.

While the new construction's condition with respect to operation, maintenance and development was assumed to be “well adaptable”, the refurbished construction's state was defined as “medium adaptable”.  Due to the low adaptability for the refurbished construction the energy consumption after refurbishment would probably be reduced to 300 kWh/m².  Those assumptions influenced the results significantly.

Results

From a climate point of view the most favourable strategy is to replace the existing construction and build a new construction. The results are illustrated in Figure 1.

Figure 1 Total emission of greenhouse gases given in CO₂-eqv. for new and refurbished constructions during 60 years.

Figure 1 shows the emissions related to producing and constructing the new building are more than twice the size of the refurbished construction.  On the other hand the emissions related to operation, maintenance and development of the refurbished construction are three times the size of emissions related to the new construction.  This is mainly explained by the low adaptability and flexibility of the refurbished construction.

This conclusion is further strengthened when comparing emissions per employee since the new construction is more area effective and makes it possible to increase the number of work places from 500 to 600.  This gives a total emission per employee of app 100 vs. 50 tonne CO2 equivalents.

The demolishing pay pack time is approximately 14 years as given in figure 2.

Figure 2 Accumulated emissions of greenhouse gases during 60 years given in CO₂-ekv. for the new and the refurbished constructions.

The results are sensitive to the estimates done, especially the merge of data for investment planning and material flow data. On the other hand the estimates are in the same order of magnitude and direction for the two different cases.

The results from this study were one of the main inputs to the decision process in the pre-construction phase.  SpareBank 1 SMN concluded to replace the existing building.  It is already demolished and the construction of the new building has started.

SpareBank 1 SMN has documented as much as 99% of the demolished materials including furniture and fixtures have been delivered to reuse or recycling.

The results from the case study show the usefulness of life cycle models as input to a decision making process in a pre-construction project.

Further work

The methodology in this study has been used to evaluate the environmental consequences of the decisions made in a feasibility phase of the project. In that respect the data used – a sort of hybrid LCA combined with the scenario strategies in LCC methodology – were suitable to distinguish between the two alternatives.  The results from the simulation of the two alternatives were considered to be suitable to advice the decision made by SpareBank 1 SMN.  In addition, the results confirm the findings in previous studies that one can accept higher environmental load in the construction phase if the way the combination of building materials and solutions are affecting each other increase the adaptability of the construction and therefore reduce the emissions during the life time of the building.

To make the model adaptable for choosing materials and solutions in the construction phase, the input data has to be product or producer specific.  In addition a critical part is the definition of the scenarios representing the life cycle planning of the construction as given in figure 3. 

Figure 3          Life cycle phases of a building (Rønning et al., 2007).

References

Rønning, A.; Vold, M. (2008):  ”Miljøvurdering av nytt hovedkontor for Sparebank 1 SMN.  Sammenligning av to alternative løsninger”, Ostfold Research, OR.10.08, Fredrikstad.

Rønning, A.; Nereng, G.; Vold, M.; Bjørberg S.; Lassen, N. (2007): “JOMAR - A Model for Accounting the Environmental Loads from Building Constructions”, OR.07.07, Ostfold Research, Fredrikstad.

UNEP (2007): “BUILDINGS AND CLIMATE CHANGE - Status, Challenges and Opportunities”, Paris.