Energy Performance of Buildings: A Comparison of Standard Assessment Methods - Nearly Zero Energy Building Refurbishment - page 194

Table 10 Refurbishment actions
Refurbishment action Case study A Case study B

Action 1 Wall—external insulation Wall—gap insulation

Action 2 Ground floor—insulation Wall—external insulation

Action 3 Wall adjacent to non-heated zone—insulation

Action 4 Heating system: boiler substitution

Action 5 Heating system: distribution system renewal

Action 6 Heating system: control system renewal

particular refurbishment actions; hence, these uncertainties affect the evaluation of
the intervention effectiveness.
For example, regarding case A (Fig. 8 ), action 4 reduces the energy needs to
88 % with respect to the base case, considering EP H, max , and to 68 % in terms of
EP H, min ; for action 3, EP H, max and EP H, min account, respectively, for 75 and
70 % of the base case.
Comparing EP H, min(action 3) and EP H, max(action 4) , the insulation of the envelope
adjacent to a non-heated zone is more effective than the boiler substitution; on the
contrary, taking into account EP H,

3) and EP H, 4) , the most max(action min(action

significant reduction in terms of energy need is associated with the boiler

substitution.
Moreover, in Fig. 9 , the results for case B are shown: the uncertainty ranges for
actions related to the heating system are negligible, while the method of energy
performance assessment causes a percentage gap between EP H, max and EP H, min
which varies from 7.09 to 16.87 %.
Finally, the uncertainty related to the calculation method could affect the cor-
rect evaluation of the energy performance assessment associated with the single
refurbishment action.
Therefore, in order to define a reliable index to compare interventions, the
average values of EPH have to be considered.

7.9 Effects of Parameters Combination

Basing on the previous analyses, significant differences in energy performance
indicators for heating just have been observed related to the uncertainties of a
single parameter, caused by the application of different calculation methodologies
allowed by UNI/TS 11300.
Consequently, the combination of different assessment method of input
parameters can lead to remarkable differences in the results. In particular, it is
possible to evaluate which assessment method can be adopted in order to minimize
or maximize the energy needs of the building approaching the A.