**5. Case studies**

#### **5.1 Life cycle assessment of energy retrofitting of a public building**

Public buildings must fulfill stricter measures and therefore energy retrofitting should be done even more carefully to justify proposed solutions beyond costs. According to that the implementation of LCIA into the decision-making process will be crucial for fulfilling the climate mitigation targets.

As an example, the assessment of energy retrofitting measures of the hospital is presented. District heat is used for heating and preparation of hot water. Hospital has a useful area Au 7405 m2 and energy needs for heating Q'NH 1614 kWh/(m2 a). At current (reference) conditions, the primary energy needed for the operation of the building service systems Qp is 1.865,362 kWh/a. Based on the parametric analysis, the planner decides on the proposed measures, and after the choice of measures, the energy, environmental, and cost assessment of the measures is carried out (**Figure 9**).

Following measures were chosen: windows replacement (Uw 3 W/m<sup>2</sup> K ! 1.1 W/m<sup>2</sup> K), thermal insulation of the facade (Uwall 1.3 W/m<sup>2</sup> <sup>K</sup> ! 0.168 W/m<sup>2</sup> K), and thermal insulation of the ceiling to the unheated attic (Uroof 0.957 W/m2 ! 0.094 W/ m2 K). The mechanical ventilation with heat recovery was not included.

After the energy retrofitting, the BDU shows the following results, the specific energy needs for heating will be reduced by 75% (Q'NH 161 kWh/m2 a ! 39 kWh/ m2 a), the final energy by 68% (Q'<sup>f</sup> 220 kWh/m<sup>2</sup> <sup>a</sup> ! 70 kWh/m<sup>2</sup> a), and the required specific primary energy for the operation of the building by 58% (Q'<sup>p</sup> 252 kWh/ m2 <sup>a</sup> ! 107 kWh/m<sup>2</sup> a) (**Figure 10**, left). The use of district heating heat and DHW will be reduced from 1380 to 320 MWh/a (**Figure 10**, middle). At this point, reference and *Evaluation of Energy Efficiency of Buildings Based on LCA and LCC Assessment… DOI: http://dx.doi.org/10.5772/intechopen.101820*

**Figure 9.** *Hospital building in Ljubljana.*

#### **Figure 10.**

*Results of energy efficiency analysis: Energy performance indicators (left), energy carriers (middle), and CO2 emissions and GWP (right) for reference project (before) and retrofitted building (after).*

renovated building data were exported to Etool for environmental and cost assessment. The results are presented for reference (before) and retrofitted building (after). The CO2 emissions will decrease by 345 tons per year. The greenhouse gases (GHG) emissions caused by measures will be 202 tons of eqCO2 per year, nevertheless, in the following years, the GHG emissions will be lower by 278 tons of eqCO2 each year. Example shows that even measures can be justified according to the environmental impact, as total GHG emissions will be lower compared to the current state (**Figure 10**, right).

The comparison of embodied energy and energy savings of energy efficiency measures shows that "energy payback time" will be shorter than 1 year, which indicates that proposed materials and technologies are sustainable (**Figure 11**).

LCIA analysis shows that all environmental indicators are significantly improved during the assessment period (selected duration of 30 years). It can be seen that the

#### **Figure 11.**

*Comparison of embodied energy in materials and technologies proposed for energy retrofitting and energy savings after 1 year of building operation.*

impact of energy efficiency measures (presented as materials) on total GWP emissions is less than 5%, while the impact of measures on the environment is the largest for ODP, while it is smallest for ADP (**Figure 12**).

The reference building causes the population of the EU (431 106 inhabitants) 0.58 years of less quality living (DALY, ReCiPe), while the retrofitted building will cause 0.48 DALY in the first year, and 0.19 DALY/a in the following years (**Figure 13**, left). The number of Eco points after retrofitting resulting from the use of energy carriers will be reduced from 68 to 59 Pt/a in the first year and to 24 Pt/a in the rest of the calculation period (**Figure 13**, right).

The LCC results are shown in **Figure 14**. Taking into account the user-defined discount factor d 3% and energy price factor e 2.8%, and assumed maintenance costs of 0.5% of the investment per year, the payback period of the proposed measures will be 16 years, while the cost of energy carriers will be reduced from the current 391 to 268 €/m<sup>2</sup> of the useful building area (**Figure 14**).

## **5.2 Comparison analysis of on-site heat and electricity generators in a single-family building**

The study case illustrates the process of evaluation technologies for heating and domestic water heating (DHW) as well as electricity generation in a single-family building with a useful area of 92 m<sup>2</sup> . The buildings are designed according to the passive buildings criteria. The building is mechanically ventilated with a heat recovery system with an efficiency of 75%; the specific power of the fans Pv,dov and Pv are 0.31 W/(m<sup>3</sup> /h). The energy needs for heating Q'NH are 11.9 kWh/(m<sup>2</sup> a). The specific power of the built-in lamps is 3 W/m<sup>2</sup> . In the reference building, the biomass pellets boiler is installed and connected to heat storage of floor heating system (600 l) and heat storage for DHW (300 l).

**Figure 12.** *LCIA analysis results of energy efficiency measures after the classification*

 *phase.*

**Figure 13.**

*LCIA analysis results of energy efficiency measures after the characterization phase.*


#### **Figure 14.**

*Payback period analysis of the investment.*

The following alternative technologies were analyzed:


*Energy efficiency analysis (LCEA).* While the specific energy needs for heating Q'NH are the same for all cases, the specific final energy demand for the operation of building service systems Q'<sup>f</sup> is the smallest for Case 3 (42 kWh/(m2 a)), and approximately the same for Cases 1 and 2 (51.3 and 53.4 kWh/(m<sup>2</sup> a)), and the highest in the case of a reference building (63 kWh/(m2 a)) (**Figure 15**).

The share of renewable energy sources (RES) for Cases 1 and 2 is provided from solar energy and environmental heat, while the required share of RES in Case 3 is provided by the transmission of electricity produced from the PV power plant to the grid (**Figure 16**).

#### *Evaluation of Energy Efficiency of Buildings Based on LCA and LCC Assessment… DOI: http://dx.doi.org/10.5772/intechopen.101820*

#### **Figure 15.**

*Energy efficiency indicators for Case 1 (left), Case 2 (middle), and Case 3 (right) in comparison with the reference case (before).*

#### **Figure 16.**

*Structure of energy carriers for Case 1 (left), Case 2 (middle), and Case 3 (right) in comparison with the reference case.*

The largest difference in the embodied energy relative to the reference case is in Case 3, and the smallest in Case 1. In Case 3, the difference in total delivered energy is the largest also for the 30-years period (**Figure 17**).

Annual CO2 emissions according to the Slovenian national legislation [20], are approximate two times higher as in the reference case, and the lowest in Case 2 (750 kg/a), i.e. by 35% compared to Case 1 and by 25% compared to Case 3. The classification of technologies according to GHG emissions (GWP) is the opposite, due to the lower use of energy carriers and the high share of RES in the electricity mix in last years in Slovenia (**Figure 18**). If another electricity supplier was selected, the GWP emissions of Case 1 would be close to 0.

**Figure 17.** *Embodied energy for Case 1 (left), Case 2 (middle), and Case 3 (right).*

#### **Figure 18.**

*Annual CO2 and GWP emissions for Case 1 (left), Case 2 (middle), and Case 3 (right) in comparison with the reference case (before).*

*Environmental impact analysis (LCIA)*. The comparison of environmental impact was done based on Eco points of heat generators and delivered energy after the first year of operation. Compared to the reference case (pellet biomass boiler) with an impact of 0.462 Pt, the gas boiler with solar thermal collectors (Case 2) has approximately the same impact (0.427 Pt). The impact is approximately half of that in the case of the heat pump (Case 1, 0.199 Pt) and doubled in the case of the gas boiler with PV (Case 3, 0.870 Pt) (**Figure 19**). The difference mainly results from the environmental pressures caused by the use of materials and the production of system elements. After the first year of operation, damage to the environment is caused only by the use of energy carriers. The use of biomass causes the lowest yearly environmental impact (0.083 Pt/a). The impact of Cases 1 and 2 is higher for 25% and the impact of Case 3 is almost doubled (0,186 Pt/a). This analysis confirmed that LCIA is a very meaningful approach when choosing technologies for nZEB.

*Cost analysis (LCCA).* Assuming 30 years of operation, the total costs (investments and energy carriers) of reference case, Cases 2 and 3 are more or less the same (between € 18,300 and € 18,500), while total costs of Case 1 are lower by 17% (€ 15,300). The cost of energy carriers is close to the investment for Cases 1 and 3, whereas the investment represents 2/3 of the total costs over the 30-years period for Case 2 (**Figure 20**). The cost input parameters are presented in Section 3 (LCCA).

Macroeconomic costs, evaluated on the basis of eqCO2 emissions costs [13] over the 30 years of operation, are the lowest at the reference case 610 €, for Case 1675 €, for Case 2750 €, and for Case 31,150 € (**Figure 21**). These ratios would be reasonable to use for creating public non-refundable financial incentives.

#### **Figure 19.**

*Eco points for the first year of operation for Case 1 (left), Case 2 (middle), and Case 3 (right) in comparison with the reference case (before).*
