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Energy efficiency, or RUE, measures in the refurbishment of high-rise buildings considered for this project have been identified from the approach taken by the so-called Trias Energica. This approach, applied to the buildings sector, prioritises actions taken to reduce energy demand and resulting CO2 emissions. First, steps must be taken to reduce fabric energy losses. The second priority is to increase the use of renewable energy sources in meeting building energy demand, and the third and final priority is to otherwise ensure a more efficient use of fossil fuels. This project only considers RUE measures, hence focusing on priorities one and three:

• Improving the thermal properties of the building fabric – that is floors, roofs, walls and windows/doors, and
• improving the efficiency of heat generation and distribution in/for the building – more efficient boilers, implementation of balancing valves, pipe insulation, implementing or improving heating controls and so on.

The emphasis on the RUE measures listed above has been placed on reducing heating demand. Building fabric measures to reduce cooling demand where applicable (apart from the measures already listed, especially solar shading devices) have also been taken into account, but have not been incorporated into the formal model. Furthermore, because this project has operated under the assumption that active cooling systems are not compatible with the objective of reducing energy demand, the efficiency of cooling generation and distribution has not been considered. Please follow the link above or here for the discussion of discussion of refurbishment measures.

In order to model the potential for energy efficiency and the cost-effectiveness of investment in RUE measures, the 28 countries considered have been categorised according to both climate and socio-economic regions. Table 1 below illustrates how this has been carried out.

EU15 countries are European Union countries that were members before 1st May 2004, EU10 countries are those that have joined the EU since, and AS3 countries are accession states. The heating degree days (HDDs) are a reflection of a country’s heating demand or climate. States in the <2700 group are warmer climate countries, countries in the 2700-3700 category experience more moderate climates, and those in the >3700 bracket have colder climates. The categorisation results in eight base regions, which have allowed the definition of eight reference high-rise buildings or base buildings, each broadly representative of the high-rise stock in its region. Figure 1 below maps out the base regions corresponding to the groupings in Table 1.

Figure 1: Base regions

Each base region has initially been considered separately and each theoretical base building has been assumed to be refurbishable in every respect for the measures considered quantitatively. The base building representative of each base region has been considered in isolation. Following the logic of the Trias Energica, building fabric measures have been considered separately as well as in a package. Heating measures have been considered differently; heating controls have been considered both in isolation and in conjunction with the building fabric package; heating system replacements should only be assessed with the building fabric package and heating controls already in place. The methodology applied in the Ecofys report for Eurima, “Cost-Effective Climate Protection in the EU Building Stock”, has been used to calculate the achievable reductions in energy demand in each base building in terms of:

• energy saved per m2 of heated floor area
• annualised/annual investment cost per m2 of heated floor area
• simple payback time
• (net) present cost per kWh of energy conserved
• (net) present cost per tonne of CO2 mitigated

Crucially, because this project considers energy efficiency as one component of the sustainable refurbishment of high-rise buildings in line with the objectives of the 3rd European Housing Ministers’ Conference on Sustainable Housing, the only costs of RUE measures considered are those that would not have occurred as part of an overall building refurbishment anyway. In the main, this implies that the cost of scaffolding has not been included in the cost of external wall insulation, for window replacement it means that only the additional cost for a high energy efficiency standard according to the best available technology principle has been considered, with the same logic applied to boiler replacement.

The reasoning for calculating cost-effectiveness on the basis of incorporating energy efficiency into a general, sustainable refurbishment approach is multi-faceted. Energy efficiency improvement is more cost-effective than if carried out separately (i.e. as a retrofit) because only the energy-related cost of the energy efficiency measures is counted. Furthermore, the VROM-commissioned survey of European housing ministries found that the two items “high-rise maintenance” and the “need for modernisation” of the high-rise stock are considered a “moderate” or “major” problem by 15 and 14 respondents respectively out of 27 housing ministries . In light of compounding factors, including “moderate” or “major” problems pertaining to a disproportionately high incidence of low-income households (17 respondents) and unemployment (15 respondents) in the high-rise stock, there is an important and widespread need for accelerating the rates of high-rise refurbishment: The incorporation of energy efficiency generates immediate, tangible financial return on refurbishment, increasing financial acceptability. In short, there is unmet demand for refurbishment, and the incorporation of energy efficiency improvements can provides additional financial ‘pull’ on refurbishment rates and concomitantly reinforces the ‘push’ of European energy and CO2-saving objectives. The summary of the cost-effectiveness assessment includes an overall comparison of the energy-related cost-effectiveness with the cost-effectiveness of retrofit, i.e. assuming energy efficiency improvement is not carried out as part of general high-rise refurbishment.

Additionally, the energy demand reduction in high-rise buildings deemed achievable in the whole base building region has been included, based on the estimations provided by the European housing ministries in response to the VROM survey.

Following a description of the measures considered quantitatively and a qualitative account of the energy efficiency measures not part of the model, the investment cost and associated cost-effectiveness of RUE measures included in the model for each base building is quantified in relation to energy savings and CO2 mitigation. This is followed by a summary and analysis of the overall results.