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Majority of studies about housing and construction industry in Great Britain indicates around 70% of existing residential buildings will be in use in 2050 which is a very big proportion compare to other developed countries. This big percentage shows the importance of green refurbishment here in the UK. Furthermore, the mayor of London's office concluded after comprehensive studies about preserve and refurbishment of residential buildings in greater London area that the best way to meet carbon reduction targets is to have a green refurbishment. There is no available software for decision making process like LCCA in present time here in the UK. LCCA software has been developed to meet the need for green refurbishment and we believe that there will be a great demand to use such software in near future. Also this software can be modified to use in different parts of the world.
Today, the majority of Construction clients ask for high quality building, lower cost and shorter construction-time. The end users of the buildings, who have to pay the utility and maintenance bills, have actually very little influence over time, cost and quality. Furthermore, Buildings represent a large and long-lasting investment in financial terms (buying a house is the single most expensive investment of majority of people in the world) as well as in other resources (Ã-berg, 2005) .
Understanding the economic aspect of building construction is very important and can be challenging. Also it is more important for green building construction and refurbishment because justifying building cost can involve somewhat more complex analysis than for conventional construction. Green buildings have so many potential benefits for their owners in the diverse range of categories such as: energy, health, water, waste, emissions, maintenance, society and environment.
The ability to express and clearly justify these benefits in an economic analysis is an important factor to understand whether or nor not the project will be conventional or green in its design and construction. LCCA software designed to help the owners and developers in decision making process when they want to refurbish residential buildings in the UK. The main objective of developed software is to justify and address all sorts of different costs before and during building refurbishment process. Hard-cost savings on energy and water are fairly straightforward to quantify and include in life cycle cost analysis. Soft costs, such as human health and environmental aspect of refurbishment process are not straightforward to justify and need more analysis regarding the location.
The life cycle costing Assessment (LCCA) process involves complex cost calculation. The ultimate goal for carrying out LCCA calculations is to aid decision-making in:
Assessing and controlling costs and identifying cost significant items and producing selection of work and expenditure planning profiles.
There are several IT tools which developed in different countries from different organisations and companies for facilitating the cost quantification and decision making processes.
The following LCCA software's have been developed in by different companies in different parts of world.
1. ACEIT (http://www.aceit.com); developed in the US and cost around $ 12000 for licence
3. BLCC 5.3 (http://www.eere.energy.gov); Developed in the US by Department of Energy
4. Kostenreferentiemodel (http://www.sbr.nl); Developed in Netherland and it is in Dutch.
5. LCCID (http://www.wbdg.org/tools/lccid.php); Developed in the US by national institute of building science
6. LCProfit (http://www.statsbygg.no); Developed in Norway and it is in Norwegian
7. LCCWare 3.0 (http://www.isograph-software.com/index.htm);
8. PARAP (http://www.bk.tudelft.nl/reh/projects/parap/);
9. Relex LCC (http://www.relexsoftware.co.uk). Developed in the UK
There are some LCCA IT tools for construction which are available for free. Commercial LCCA tools usually provide some advanced functions, such as integration with CAD tools. Certain commercial LCCA tools are generic, and are usually used in the manufacturing and production industry. These tools require the formulation of equations for quantifying the life cycle costs for construction projects. Therefore, additional efforts are needed if these tools are selected.
All the tools provide Net Present Value (NPV) as the primary measures for the projects. BLCC 5.3, which was developed by American National Institute of Standards and Technology (NIST), also provides other measures such as NS (Net Saving) and SIR (Saving to Investment Ratio). Most of the tools only generate deterministic results, though it is recognised in the TG4 report (European Union Task Group on Life Cycle Assessment) that uncertainties and risks should be taken into account in the LCCA process.
It is necessary to remind that some tools were developed based on the LCCA standards of certain countries. Therefore, changes, if allowed in the software package, must be made if one of these tools is to be adopted in other country.
LCA for Buildings
LCA is a measurement tool, a way to measure the environmental performance of products over their life cycle from cradle (where the raw materials are extracted) to grave (where the product is finally disposed). In fact LCA is the only science-based and credible tool that is actually designed to measure the environmental impacts of product.
In the life cycle of a building, various natural resources are consumed, including energy resources, water, land, and minerals, and many kinds of pollutants are released back to the global and regional environment. These environmental inputs and outputs result in global warming, acidification, air pollution, deforestation, etc. which inflict damage on human health, primary production, natural resources and biodiversity. The use of energy for producing materials and operating buildings, either directly or indirectly, contributes to air pollution (Suzuki and Oka, 1998) . Furthermore, there have been signs that certain human activities such as industrialisation and urbanisation have caused irrecoverable environmental impacts to the earth. The building sector, constituting 30-40% of the society's total energy demand and approximately 44% of the total material use as well as roughly 1/3 of the total CO2 emission (Erlandsson M, Borg M, 2003)  also it has been identified as one of the main factors of greenhouse gas emissions.
There is no doubt that reducing the environmental burden of the construction industry is essential to sustainable development. Also it is clear that environmental impact associated with buildings is as much an issue as financial cost in their construction and use (Ofori, 1992) . In particular, now that the ''Kyoto Protocol'' has already gone into effect, this is an urgent assignment.
Considering the refurbishment of existing building stock is very important especially in most European cities which the majority of buildings have historical values and are quite old. It is obvious that one of the most important factors to meet carbon reduction targets is the green refurbishment of existing stocks especially for residential buildings. All these mentioned facts make the refurbishment option very viable and probably the best solution to meet carbon reduction targets.
Analytical model/programme LCCA Program
Developed LCCA program is for residential building refurbishment in the UK. It is a certified rating system based on building energy performance and environmental burden, using different equations like life cycle cost assessment as well as checklist. LCCA software is categorised in building assessment system like LEED in North America or breeam here in the UK.
It is important to mention that generally building assessment systems rate the effects of buildings design, construction, operation and environmental impact etc. this is a complicated determination, as each aspect has different unites of measurements and applies at different physical scales. Environmental effects can be evaluated at local, regional, national and global scales, for example in two environmental equations which used in LCCA program, the information has been calculated in Sweden but it is applicable in the UK.
One of the most important objectives to develop LCCA software was to be as user friendly as possible and because the target users are the home owners and developers, the software designed to be as simple as possible. There are seven different equations used in LCCA spreadsheets which five of them are cost related and two of them are to calculate the environmental impacts. Using this simple but effective software can help the decision making process and can promote green refurbishment. It is also important to mention that parallel effects of successful building assessment systems could also help facilitate otherwise difficult political goals like emission reduction targets or London mayor plans for big scale residential building refurbishment.
There were two different ways to develop the LCCA software. Either to use a single number to describe the green refurbishment or to provide an array of numbers for the same purpose, a single number representing the green indicator for the building is easy to understand. But if a single number is used to show the green refurbishment then the system should somehow convert the different unites describing the energy use, overall cost and environmental impact.
Calculating different items and combining the result to get a single number is a difficult method at best. Paradoxically, however, both the advantage and disadvantage of the single-number assessment is its simplicity.
Alternatively, we could employ an array of numbers or graphs that shows the building's performance in major areas like life cycle cost analysis, energy performance and environmental impacts compared to conventional construction. This method needs more detailed information about each item and its complexity makes it difficult to compare buildings, depending on the range of factors. LCCA software is a mix of two different methods as it chose a Bedzed green development as a benchmark for green building and compared different buildings to Bedzed from different points of view to indicate the green refurbishment. However, the green indicator counts as a single number assessment. Furthermore, the checklist has been used to verify the results. Figure (1) shows part of the front page of LCCA software which by using drop-down boxes the user can understand the embodied carbon of different materials which used for building refurbishment.
Figure 1: Calculated embodied carbon
Figure 2: LCCA front page
Case studies included six different buildings in different parts of Greater London. Furthermore, the main focus of this study was on the UK residential buildings, the objective of these case studies was to understand the definition of green building before and during the renovation process. Spreadsheet data used to find out the green indicator to use for developed software. Furthermore, Bedzed project selected as a bench mark for green building as it is the only zero carbon residential building complex in greater London Area and although Bedzed have not been refurbished yet but it is green by definition.
Comparison between different types of buildings is not very accurate but due to lack of database for residential buildings, it was necessary to study and analyze all available residential buildings within the greater London area.
The average area size of residential buildings in the UK is about 120 square meters which is the average area size of our case studies as well. The buildings have been chosen from different boroughs in London (Sutton, Royal Borough of Kensington and Chelsea, Islington and Camden) the advantage of choosing different boroughs is although the building types might be the same but the energy consumption trend is different.
Bedzed is in borough of Sutton and it has been build ten years ago and is not refurbished yet, the average area size in bedzed housing complex is about 100 square meters. It has been built using the latest renewable technologies which was available in the market during construction period. Energy usage of Bedzed is low compare to normal residential buildings across UK which is mainly the result of green design and structure as well as the people who live in the complex. Four people lives in this flat and The construction cost for each flat calculated around £160000, operational cost £500 which is very low compare to the rest of buildings in this study because of green construction, LCC for 30 years calculated at £ 50692.65, Net Price Value £500, Present Value of Life Cycle cost £ 200500, the energy retrofit (R) for building materials calculated at £17.90, whole life cost (WLC) £220500, Weighting Environmental Input (WI) 8003.91 which is the same in all case studies. Environmental Input index 83240.66, LCCE for 30 years £ 19435, LCCE for 30yrs /Sample CC £ 0.383388913, Energy bill per square meter £5, LCCE for 30yrs /LCCE for 1year £ 22.11, LCCE 30 years per square meter £ 194.35.
Kensington flat is privately owned property and located in the royal borough of Kensington and Chelsea. The flat is in the Edwardian building which was built in the beginning of the 19th century. The area size of the house is 120 square meter. There was no major refurbishment in recent years, but there is a plan for a complete one in 2010. Inside the flat is the typical converted Edwardian form. Furthermore, the heating system in the flat works with electricity and there is no usage of natural gas in any appliances. Annual energy bill is £2400 which is a very high amount of money to pay compare to size of the flat. Moreover, windows are single glaze and all heaters are beneath them. Also, boiler is very old and inefficient electrical one. The estimation for construction cost in this flat is around £192 000, the operational cost £4000, Sample Cycle Cost (30 years) £ 296166.80 , Net Price Value calculated at £155600, Present Value of Life Cycle Cost £145546, the energy retrofit (R) for building materials calculated at £85.94, whole life cost (WLC) £105898, Weighting Environmental Input (WI) 8003.91 which is the same in all case studies. Environmental Input index 283545.92 compare to the bedzed the difference is significant as the bedzed constructed to be green housing, LCCE for 30 years £154997 , LCCE for 30yrs /Sample CC £ 0.523343602, Energy bill per square meter £20, LCCE for 30yrs /LCCE for 1year £ 21.25, LCCE 30 years per square meter £ 1291.64.
Knightsbridge flat in royal borough of Kensington and Chelsea has an area equal to 80 square meters and it was built in 1835 as a trace house and converted into flats in 1970. The occupancy rate is two in this flat. According to the landlord the building has been refurbished two years ago. However, there is no significant reduction in energy bills. The reason is the windows are still single glaze and boiler is an inefficient 30 years old electrical boiler. Also, there is no proper insulation in the building. Study of this flat is a good reminder to the property developers and landlords that it is better to start the renovation and refurbishment of the buildings from windows and old boilers.
The study results for Knightsbridge flat are: estimation for construction cost is around £128 000, the operational cost £1000, Sample Cycle Cost (30 years) £ 245862, Net Price Value calculated at £155600, Present Value of Life Cycle Cost £220500, the energy retrofit (R) for building materials calculated at £10.74, whole life cost (WLC) £242300, Weighting Environmental Input (WI) 8003.91 which is the same in all case studies. Environmental Input index 300517.18which is close to Kensington flat, LCCE for 30 years £124719, LCCE for 30yrs /Sample CC £ 0.507272888, Energy bill per square meter £22.5, LCCE for 30yrs /LCCE for 1year £21.36, LCCE 30 years per square meter £ 1558.99.
Normal Victorian house is in borough of Camden. This case study is particularly interesting because I had a chance to study similar building which has been comprehensively refurbished. It is two story building with three bedrooms. The building has been refurbished 8 years ago, so there are double blaze windows and the heating system is in a good condition and the loft is fully insulated. The whole area of the building is 120 square meter. The annual energy bill is £2400, which shows the works were done on building correctly. As we should consider, the building is fully occupied trough the year. The study results for this flat are: estimation for construction cost is around £192 000, the operational cost £2400, Sample Cycle Cost (30 years) £ 72805.15, Net Price Value calculated at £ 153600, Present Value of Life Cycle Cost £ 145546, the energy retrofit (R) for building materials calculated at £85.94 which is the same as Kensington flat, whole life cost (WLC) £ 105898, Weighting Environmental Input (WI) 8003.91 which is the same in all case studies. Environmental Input index 255046.07, LCCE for 30 years £ 80099.14 , LCCE for 30yrs /Sample CC £ 1.100185083, Energy bill per square meter £20, LCCE for 30yrs /LCCE for 1year £21.31, LCCE 30 years per square meter £ 667.49.
EcoVictorian house is in borough of Camden and has six bedrooms. The building has been renovated to reduce more than 80% of the CO2 emissions produced by living in the house. The renovations included numerous innovative CO2 reduction technologies. The biggest CO2 saving was achieved through insulation. In most houses, including this one, the majority of energy is used for heating, and much of this heat is simply lost through walls, windows, floors and roofs, with walls being the primary source of heat loss.
The house, like all housing built before 1930, has solid walls. Properties built after 1930 tend to have cavity walls which consist of two layers with a thin space or "cavity" in between. The Eco house has been monitored 24/7 by university college of London however the information is not available to public. Since the big portion of residential buildings in the United Kingdom are Victorian houses, we can use this particular project as a bench mark to understand the green indicator for our software.
Spreadsheet results for this flat are: estimation for construction cost is around £192 000, the operational cost £1000, Sample Cycle Cost (30 years) £192600, Net Price Value calculated at £192602, Present Value of Life Cycle Cost £145546, the energy retrofit (R) for building materials calculated at £35.81, whole life cost (WLC) £ 105898, Weighting Environmental Input (WI) 8003.91 which is the same in all case studies. Environmental Input index 173862.71, LCCE for 30 years £ 54216.77, LCCE for 30yrs /Sample CC £ 0.281499325, Energy bill per square meter £8.3, LCCE for 30yrs /LCCE for 1year £21.86, LCCE 30 years per square meter £451.81.
Queens Gate flat is in a borough of Kensington and Chelsea and the size of flat is 85 square meter. The occupancy rate of this flat is three people. Flat has been refurbished recently but as previous flats the land lord didn't change the boiler (old full electrical boiler) and all the windows are single glazing. Furthermore, there is no proper insulation in this property.
Spreadsheet results for this flat are: estimation for construction cost is around £136 000, the operational cost £3000, Sample Cycle Cost (30 years) £182705.85, Net Price Value calculated at £446000, Present Value of Life Cycle Cost £155000, the energy retrofit (R) for building materials calculated at £71.61, whole life cost (WLC) £157000, Weighting Environmental Input (WI) 8003.91 which is the same in all case studies. Environmental Input index 360065.05 , LCCE for 30 years £ 144810, LCCE for 30yrs /Sample CC £ 0.792585459, Energy bill per square meter £23.5, LCCE for 30yrs /LCCE for 1year £21.83, LCCE 30 years per square meter £1703.65.
LCCA software has been developed to help the people with basic knowledge of refurbishment in decision making process. We tried to design LCCA program as user friendly as possible and all Ergonomical measurements have been applied in design process. We believe that there will be a big demand for green refurbishment in near future and using assessment programs are necessary part of this process.