ZEMCH 2015 - International Conference Proceedings | Page 79

inflation rates and the anticipated life of the component or facility. For these reasons, some researchers tried to use economic risk assessment, using either probabilistic or sensitivity approach,
to evaluate some of these uncertainties (Cole & Sterner 2000:368–375). In this way it’s possible to
lessen the uncertainties in the result by performing sensitivity analysis over the parameters which
are of the greatest importance to the result (Sterner 2000:387–393).
A considerable number of studies have performed sensitivity analysis regarding their LCC calculations. According to (Boermans, Hermelink, & Schimschar 2011) a sensitivity analysis was carried
out on three different energy price development scenarios–i.e. high (+30%), medium (base case),
low (-30%) - with two individual measure packages over a case study to assess the sensitivity of
results. Their comparison illustrated that energy price evolution can change the optimum cost
level; in the low energy price scenario the lowest global cost goes for the package with higher
energy needs while for high price scenario ,with 25% growth in global cost, the package with
lower energy needs comes out as the lowest one. Also impact of different interest rates on results
was examined when applying lower (2%) or higher (6%) rates, compared to a base case of 4%. It
was shown that with a lower interest rate, investigation on energy efficiency measures is more
beneficial. Similar results were observed in a study in Denmark (Marszal & Heiselberg, 2011) which
implemented for a multi-storey residential netZEB.
In the context of Estonia (Jarek Kurnitski et al. 2011), a cost optimal and nZEB energy performance
level calculation was conducted on a detached house. LCC analysis was carried out for four construction concepts as well as all relevant heating systems. By comparison of “global incremental
energy performance related costs”, the lowest PV (present value) of cost was found. Although
primary calculations were done by energy escalation rate (e) of 2%, it was observed that results
are sensitive to interest rates and with a higher rate (e=3%) the cost optimal is shifted to the left
toward lower primary energy needs however cost optimal solution remained the same case. In
the other side with a lower value (e=1%) cost optimal shifted to right and cases with lower PV and
higher energy needs became cost optimal. Similar results were also observed in (J Kurnitski et al.
2013:183) where a sensitivity analysis on the value of real interest rate was performed in the cost
optimal calculations of a representative Estonian apartment building and by lowering the interest
rate, cost optimal level was shifted to lower primary energy needs.
Additionally, It was argued in (Pikas et al. 2014:30–42) that although nZEB requirements (≤100
kWh/m2yr in Estonian context) are not the cost optimal solutions at this moment, by performing
some sensitivity analysis it has been found out that they may become cost optimal in near future
under particular values of energy escalation rate and probable construction costs reduction of
some specific element. In Finland (Hamdy, Hasan, & Siren 2013:189–203), the sensitivity analysis
regarding energy price escalation rate (e) for a cost optimal level of a single family house -within
the range from 2 to15%- showed that investing on energy saving measures and renewable energy
sources is more feasible at higher energy price escalation rates.
Some authors in Australia (Morrissey & Horne 2011:915–924) applied more than one discount rate
for samples consisting of 80 house plans. They used a 3.5% discount rate for 0–30 year period,
and 3% for 30–70 years. Moreover, this study investigated two different cost scenarios for gas and
electricity with low and high prices and it was observed that the differences between energy
costs at high and low scenarios were marginal at the 10 years-time horizon but after 25 years, an
approximate 25% difference in values appeared in energy savings between high and low energy
price scenarios.

Research Aim
By taking advantage of the experiences of previous researches on uncertainty analysis in LCC calculations, this paper aims to utilize EU suggested methodology on a reference building in Italian

Uncertainty effects of input data on cost optimal NZEB performance analysis

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