**3. Building description unit**

The national EPBD certification computer tool was upgraded into the BDU by creating additional database files called "LCA" that includes information on the most recognized environmental impact indicators and cost. If the designer installs the "LCA" marked material into the building structure or the "LCA" marked component of the building service system, this will not only affect energy demand evaluation, but additional inventory data for LCIA and LCCA will be created. Because LCA indicators are developed per functional unit, the total value of each indicator (environmental impact or cost) is determined according to the building plan and stored in BDU. At the current stage of software development, inventory data are available for most commonly used construction materials, windows and doors as building structures, and heat generators as well as photovoltaic (PV) modules. Nevertheless, the inventory LCA database is open source and could be enlarged by the new elements with user-provided data (**Figure 3**).

#### **3.1 Life cycle environmental impact assessment algorithm**

The environmental impact indicators were chosen from Environment Product Declaration (EPD) certificates. Following damage categories are included: emissions of greenhouse gases causing global climate change weighted by Greenhouse Warming Potential (GWP) and expressed as CO2 equivalent, emissions of gases that cause depletion of stratospheric ozone weighted by Ozone Depletion Potential (ODP) and

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


#### **Figure 3.**

*If the designer wants to include certain materials (left), building structure, components of heat or electricity generation system (right), or particular energy carrier into the LCA assessment, it should be selected from the predefined "LCA" inventory database.*

expressed as CFC-11 equivalent, emissions of gases that cause acidification of precipitation weighted by Acidification Potential (AP) expressed in SO2 equivalent, eutrophication by weighted emissions by Eutrophication Potential EP as PO4 <sup>3</sup>� equivalent, tropospheric ozone creation by Tropospheric Ozone Forming Potential (TOFP) as C2H4 equivalent, use of abiotic sources as Abiotic Depletion Potential – Elements (ADPE) as Sb equivalent and as Abiotic Depletion Potential – Fossil (ADPF) in MJ. Data from Ökobaudat [6], Environdec EPD Database [7], Eco-Platform [8], IBU [9], and manufactures data (i.e. Knauf Insulation [10]) were used in database integrated in BDU.

#### *3.1.1 Life cycle environmental impact data of materials and building structures*

Indicators presented in Chapter 3.1 are defined per reference unit. This is 1 m<sup>3</sup> of built-in material, except for thin layers, such as water vapor or wind barriers for which the reference unit is 1 m2 . BDU was adapted to calculate the total amount of built-in LCA materials and the total value of a particular environmental impact indicator. LCIA data of windows and doors are entered by default as such building structures are most commonly replaced as part of the energy renovation. To enable LCIA regardless of the size and type of the windows, regression models of each environmental impact indicator were developed taking into account the window glazing, spacer, and frame material. Factors are integrated into the BDU in the following form (as an example of greenhouse gas emissions):

$$\text{GWP}\_{\text{w}} = \mathbf{A}\_{\text{w}} \cdot \mathbf{f}\_{\text{g}} \cdot \mathbf{GWP}\_{\text{g}} + \frac{\mathbf{A}\_{\text{w}} \cdot \left(\mathbf{1} - \mathbf{f}\_{\text{g}}\right)}{\mathbf{d}\_{\text{frame}}} \left(\mathbf{GWP}\_{\text{frame}} + \mathbf{GWP}\_{\text{spac}}\right) \left(\mathbf{kg} \,\mathbf{CO}\_{\text{2eq}}\right) \tag{1}$$

where GWPw is the impact factor of global climate change related to the window with area Aw (m<sup>2</sup> ), fg is the ratio of glazing in the total window area, dframe is the width of the frame (by default 0.1 m for wood and 0.15 m for plastic and metal frame), and GWPg, GWPframe, GWPspac are specific impact factors per unit of glazing, frame, and spacer respectively. Default environment impact factors for windows and reference units are presented in **Table 1**.


#### **Table 1.**

*Environment impact factors and reference units of window elements; data are average value gathered from oekodatbaudat.de and include A1–A3 LCA modules.*

#### *3.1.2 Life cycle environmental impact data of selected heat and electricity generators*

Replacement of old heat generators and installing the solar thermal system or photovoltaic system are very common measures to increase energy efficiency and share renewable energy sources in buildings. LCIA data gathered from EPD databases [6–9] are integrated into BDU for the following on-site energy generators of buildings service systems: condensate gas boilers, biomass boilers, heat pumps, and solar thermal systems. Heat storage can also be included in LCIA and LCCA. For each LCIA indicator, the same form of regression model was developed and regression coefficients a0, a1, and a2 were determined from the available database or research sources including A1–A3 LCA module. Coefficients were determined for boilers with design thermal power (as reference unit) between 20 and 400 kW, for heat pumps with design thermal power between 10 and 70 kW, and storage with the volume between 50 and 2500 liters. LCIA regression model was developed for PV modules with different PV cell technologies as well. In this case reference unit is the area of PV modules. Impact factors are integrated into the BDU in the following form (as an example of stratospheric ozone depletion potential):

$$\text{ODP}\_{\text{gen}} = \mathbf{a}\_{0,\text{gen}} + \mathbf{a}\_{1,\text{gen}} \cdot \mathbf{P}\_{\text{gen}} + \mathbf{a}\_{2,\text{gen}} \cdot \mathbf{P}\_{\text{gen}}^2 \quad \text{(kg CFC 11\_{eq})}$$

$$\text{ODP}\_{\text{sol}} = \mathbf{1.25} \cdot \mathbf{a}\_{1,\text{sol}} \cdot \mathbf{A}\_{\text{sc}} \text{ (kg CFC 11\_{eq})}$$

$$\text{ODP}\_{\text{hs}} = \mathbf{a}\_{0,\text{hs}} + \mathbf{a}\_{1,\text{hs}} \cdot \mathbf{V}\_{\text{hs}} + \mathbf{a}\_{2,\text{hs}} \cdot \mathbf{V}\_{\text{hs}}^2 \text{ (kg CFC 11\_{eq})}$$

$$\text{ODP}\_{\text{pv}} = \mathbf{a}\_{1,\text{pv}} \cdot \mathbf{A}\_{\text{pv}} \text{ (kg CFC 11\_{eq})} \tag{2}$$

where a0,x, a1,x, and a2,x are regression coefficients for a particular building service system, Pgen (kW) is designed thermal power of heat generator, Asc is the area of solar collectors (m<sup>2</sup> ), Vhs is the volume of heat storage (l), and Apv is the area of PV modules (m<sup>2</sup> ). Default values of regression coefficients are shown in **Table 2**.


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


**Table 2.**

*Environment impact factors and reference units of selected elements of building service systems; data represent the average value gathered from Ökobaudat [6], Environdec EPD database [7] and research publications [2, 11], and include A1–A3 LCA modules.*

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

#### *3.1.3 Life cycle environmental impact data of energy carriers*

The database of environmental impact indicators of fuels is summarized from the EPD certificates gathered from Ökobaudat [6] and Environdec EPD database [7]. The reference unit is kWh of heat. The values of indicators consist of A1–A3 LCA modules. Impact indicators for electricity were determined based on EPD certificates of various technologies of electricity generation. Values are increased by a unified distribution factor. There is also an option to select electricity from the list of local electricity suppliers. Default values of impact factors of energy carriers are shown in **Table 3**. Besides default data, users can add their own data and this data will be available to use as an "LCA" marked element automatically.

#### **3.2 Life cycle cost assessment**

The important requirement of the recast EPBD is that EC Member States must set minimum requirements for energy performance of buildings in such a way that a costoptimal solution is provided. The Directive [1] also defines the concept of a costoptimal measure as a measure leading to the lowest total cost during the period of building operation. To assess the cost-effectiveness of energy efficiency measures, the LCCA module has been introduced in BDU. In the frame of the assessment, by discounting costs and savings, cash flow LCCn is determined in a pre-defined time period of n years and the investment with the highest positive cash flow can be found. In the BDU, the total cost of "LCA" elements is determined meanwhile cash flow is determined in Etool in which the value of the investment is comparative, based on the


#### **Table 3.**

*Environment impact factors and reference units of energy carriers.*

calculated cost savings of the energy carriers in refurbished and reference building. The cash flow at the end of each year and the end of the calculation period n is determined by the equation:

$$\text{LCC}\_{\mathbf{n}} = \sum\_{\mathbf{i}=0}^{\mathbf{n}} \left[ (\mathbf{c}\_{\text{inv}} + \mathbf{c}\_{\text{man}})\_{\mathbf{i}} \cdot (\mathbf{1} + \mathbf{d})^{\mathbf{i}} + \sum\_{j=1}^{\mathbf{m}} \mathbf{c}\_{\mathbf{e},j} \cdot \frac{\left(\mathbf{1} + \mathbf{e}\_{\text{j}}\right)^{\mathbf{i}}}{\left(\mathbf{1} + \mathbf{d}\right)^{\mathbf{i}}} \right] - \mathbf{V}\_{\text{(n)}}(\mathbf{e}) \tag{3}$$

where i is the year numerator, n is LCA calculation period (years), and m is the number of energy carriers needed for the operation of the buildings. cinv are investment costs (€), cman yearly maintenance costs (/a), and ce,j is yearly costs of jth energy carriers (€/a), d is the discount rate, ce,j is forecasted yearly cost increase of jth energy carrier, and V(n) is the residual value of the built-in LCA element at the end of LCA calculation period. Guidelines accompanying Commission Delegated Regulation [13] suggested that for macroeconomic analysis, an annual discount factor of 3% should be assumed. The same document predicts the annual increase in energy carrier prices – 2.8% for natural gas and light heating oil prices, 2% for coal, and 9% increase in electricity prices (until 2030). The annual cost of maintenance of technical systems is assumed to be between 2 and 5% in cost-effectiveness studies [14]. The residual value of the measures is determined based on the expected lifetime of the measures. Standard EN 15459 [15] predicts the duration period of different energy efficiency measured – 50 years for thermal insulation on the building envelope, 30 years for building furniture, and 15 years for technical systems. According to the proposed LCA calculation period (30 years for residential building), this means that at the end of this period thermal insulation will have a residual discounted value of 16.5% of the investment value, taking into account the discount factor of 3%. The discounted residual value for building furniture will be EUR 0, while at least one replacement of technical systems will be required. For technical systems, the cost of replacement is discounted.

#### *3.2.1 Cost database of materials and building structures*

In parallel to inventory data of environmental indicators, costs are stored in BDU. For materials having reference units defined by the volume, costs in the database are defined as constant or as a linear function depending on the depth of the built material layer. Default costs are determined according to market research but could be modified by the user. The regression model for determination of costs of windows and doors was developed based on the hydraulic diameter. In the case of the window cw, regression model is developed in form of:

$$\mathbf{c}\_{\mathbf{w}} = \mathbf{b}\_{0,\mathbf{w}} + \mathbf{b}\_{1,\mathbf{w}} \cdot \frac{\mathbf{4} \cdot \mathbf{A}\_{\mathbf{w}}}{\mathbf{P}\_{\mathbf{w}}} = \mathbf{b}\_{0,\mathbf{w}} + \mathbf{b}\_{1,\mathbf{w}} \cdot \frac{\mathbf{4} \cdot \mathbf{A}\_{\mathbf{w}}}{\frac{(1 - \mathbf{f}\_{\mathbf{g}}) \cdot \mathbf{A}\_{\mathbf{w}}}{\mathbf{d}\_{\mathbf{f}\mathbf{m}\mathbf{w}}} + \mathbf{4} \cdot \mathbf{d}\_{\mathbf{f}\mathbf{m}\mathbf{e}}} \tag{4}$$

where b0,w and b1,w are regression coefficients, dw,H is the hydraulic diameter of window (m), Aw is window area (m<sup>2</sup> ), Pw in window perimeter (m), fg is the ratio of glazing in the total window area, dframe is the width of the frame (m). The regression model is valid for the windows with an area up to 4 m2 . In **Figure 4** costs of market available windows with wood frame and according to the hydraulic diameter of the

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

#### **Figure 4.**

*Cost of windows with a wooden frame and two-layer glazing according to hydraulic diameter of the window; data gathered from Slovenian market overview [2].*

window are shown. Data for double and triple glazing, as well as for wooden, plastic, and metal frames were gathered.

#### *3.2.2 Cost database of building service systems elements*

Investment cost of elements of building service systems integrated into BDU as default values are available for the following components: condensation gas boilers, biomass boilers, A/W, S/W and W/W heat pumps, solar heating systems with heat storage, mono, poly, CdTe, and CIGS PV modules. Regression models in similar form as environment impacts indicators (Eq. (2)) were developed with new regression coefficients as presented in **Table 4**. Regression coefficients were determined for boilers with design heating power 10–136 kW, for heat pumps thermal power from 5 to 90 kW, and for heat storage with volume 50–2500 liters and 1 m<sup>2</sup> of solar collector or PV module area.

#### *3.2.3 Cost database for energy carriers*

The cost of energy carriers was determined per kWh from data published by the Statistical Office of the Republic of Slovenia [16] and the Slovenian market price overview.

## **4. Life cycle assessment tool**

BDU forms necessary data needed for LCEA, LCIA, and LCCA. It is designed in a way that two selected projects' data can be exported in the LCA evaluation tool Etool, one as a reference and the other as a designed one. This allows immediate evaluation of proposed measures for increasing the energy efficiency of buildings. Etool was developed in MS Excel software. Following the requirements of EPBD and content of environmental product declarations (EPD) the LCA metrics includes presentation of:


*Note: Assembly costs are taken into account as 20% (for heat pumps and solar collectors) and 10% (for the rest of the heat generators, PV, and heat storage) of investment costs.*

#### **Table 4.**

*Regression coefficients in regression cost models of selected elements of building service systems.*

• LCEA – yearly specific energy needs for heating (Q'NH), final energy (Q'f) for the operation of EPBD building service systems, primary energy needed (Q'p), and renewable energy ratio in delivered (final) energy are shown as the specific value per unit of useful area (**Figure 5**). These values allow the designer to overview the fulfillment of nZEB requirements. On the second level of LCEA (**Figure 6**), the absolute energy demand is shown, and delivered (final) energy is presented by energy carriers. Besides energy demand, emission of CO2, as well as the emission of greenhouse gasses expressed as CO2 equivalent is shown as the most recognizable environment impact indicators. Meanwhile, emissions of CO2 are determined by energy carrier use, CO2eq includes LCA emissions (A1–A3) resulting from the implementation of measures taken to increase the energy performance of the building. The impacts of all building elements taken from the "LCA" database or marked as "LCA" are summarized. For analyzed (e.g. renovated) buildings, the decrease of energy demand can be compared with the embodied energy of "LCA" elements through user-selected calculation period. Data of embodied energy is taken as the value of Abiotic Depletion Potential – Fossil (ADPF) environmental impact indicator of "LCA" elements from modules A1–A3.

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

**Figure 5.** *Display of nZEB energy efficiency metrics at the base level of LCEA.*

#### **Figure 6.**

*Second level of LCEA metrics displayed in Etool.*

• LCIA – LCA environmental impact assessment is performed in three phases – through classification, characterization, and normalization phase (**Figure 7**). In the classification phase material and energy flows as well as the emission of

**Figure 7.** *Results of LCIA metrics.*

pollutants equivalents related to LCA building elements, including energy carriers, are summarized during the user-selected LCA calculation period into seven pre-selected impact categories. Values are presented as physical quantities (e.g. kg, MJ). In the characterization phase sum of environmental impacts expressed by equivalents (e.g. AP or EP) are weighed by impact factors (e.g. global warming potential GWP100 of particular greenhouse gas) and classified into damage categories. The number of damage categories defers among the methods. As most commonly used, damage categories included in IMPACT 2002+ [17, 18] and ReCiPe [19] method could be evaluated in Etool. IMPACT 2002+ consists of four damage categories: climate change (global warming), human health measured in DALY (Disability Adjusted Life Years), ecosystem quality measured as potential loss of ecosystems as a consequence of acidification and eutrophication and expressed as PDF (Potentially Disappeared Fraction), and damage to reserves of natural resources expressed in MJ. ReCiPe method assessed environmental impact only through three damage categories because global warming is included through the human health damage category. At this point, results are presented as mid-point environmental impacts to the global environment (e.g. DALY per year or MJ per year). By normalization, impacts of the analyzed building (reference and designed) are compared to the total environmental impacts in the reference system e.g. European Union and total impacts could be normalized to each person, with an assumed number of inhabitants 410 <sup>10</sup><sup>6</sup> . Mid-point LCIA results in Etool are presented as total

**Figure 8.** *Results of LCCA metrics.*
