IBU study shows that the use of prod­ucts with an EPD has a pos­i­tive impact on the eco­log­i­cal foot­print of a build­ing and its DGNB rating

When a build­ing is cer­ti­fied, for exam­ple using the DGNB sys­tem – the sys­tem devel­oped by the Ger­man Sus­tain­able Build­ing Coun­cil – its eco­log­i­cal per­for­mance is rat­ed based on fac­tors includ­ing the key fig­ures from its life cycle assess­ment. The build­ing life cycle assess­ment (LCA) can either be based on gener­ic, less sound data or on man­u­fac­tur­er-spe­cif­ic and inde­pen­dent­ly ver­i­fied prod­uct data from Envi­ron­men­tal Prod­uct Dec­la­ra­tions, or EPDs. A study com­mis­sioned by the Insti­tut Bauen und Umwelt e.V. (IBU) at the Fraun­hofer Insti­tute for Build­ing Physics (IBP) exam­ined whether and to what extent the build­ing LCA improves when using EPD data com­pared with gener­ic data. The study also inves­ti­gat­ed how the dif­fer­ent data bases affect the DGNB assess­ment of a building’s indi­vid­ual envi­ron­men­tal indicators.

Influ­ence of build­ing prod­ucts on the building’s LCA increases

The life cycle assess­ment of a build­ing, i.e. its eco­log­i­cal foot­print, is made up of the envi­ron­men­tal impacts of the build­ing fab­ric (includ­ing min­ing of raw mate­ri­als, pro­duc­tion, main­te­nance and dis­pos­al) and the cost of run­ning the build­ing (e.g. elec­tric­i­ty and heat require­ments). In build­ings with high ener­gy require­ments, the total envi­ron­men­tal impact is dom­i­nat­ed by the util­i­sa­tion phase. In “3‑litre hous­es”, on the oth­er hand, the ratio between the build­ing fab­ric and the util­i­sa­tion phase is vir­tu­al­ly bal­anced. “The more ener­gy-effi­cient the build­ings become, the high­er the ratio of the build­ing fab­ric in the envi­ron­men­tal impact of the build­ing”, explains study author Dr. Ing. Johannes Gant­ner. “As a result, the impor­tance of build­ing mate­ri­als will con­tin­ue to increase and plan­ners and builders are focus­ing more atten­tion on the selec­tion of materials”.

Envi­ron­men­tal Prod­uct Dec­la­ra­tions (EPDs) are prefer­able to gener­ic data

The LCA data sets dis­tin­guish between gener­ic data and man­u­fac­tur­er-spe­cif­ic EPD data. Gener­ic data is cal­cu­lat­ed on the basis of gen­er­al­ly avail­able sta­tis­tics and oth­er sources of lit­er­a­ture and made avail­able, for exam­ple, in the ÖKOBAUDAT, a Fed­er­al Gov­ern­ment life cycle assess­ment data­base. Gener­ic data is asso­ci­at­ed with a high degree of uncer­tain­ty and was used espe­cial­ly in the infan­cy of build­ing sus­tain­abil­i­ty assess­ments, when only a small num­ber of man­u­fac­tur­ers were able to pro­vide indi­vid­ual key fig­ures in the form of EPDs.

In con­trast, EPDs are based on the actu­al pro­duc­tion data from a spe­cif­ic man­u­fac­tur­er or man­u­fac­tur­er group. EPDs from the IBU must be reviewed by an inde­pen­dent third par­ty pri­or to pub­li­ca­tion; in this respect, the LCA data they con­tain has a high degree of cer­tain­ty and – accord­ing to DGNB require­ments – should be used in pref­er­ence to gen­er­al, gener­ic LCA data.

Cal­cu­lat­ing the life cycle assess­ments of a rep­re­sen­ta­tive office building

The study car­ried out by the IBP is based on a rep­re­sen­ta­tive office build­ing in sol­id con­struc­tion for which the build­ing prod­ucts and the ener­gy require­ments for two ener­gy stan­dards (“stan­dard” and “future”) were deter­mined in advance. For both build­ing vari­ants, the envi­ron­men­tal effects were first cal­cu­lat­ed using gener­ic data from the ÖKOBAUDAT (as at 2016). For the com­par­a­tive analy­sis, the gener­ic build­ing mate­ri­als data was then replaced with data from man­u­fac­tur­er-spe­cif­ic EPDs. The replace­ment cycles and ener­gy con­sump­tion were cal­cu­lat­ed for a peri­od of 50 years, in accor­dance with the DGNB requirements.

Improve­ment in the life cycle assess­ment when using EPDs

The results of the LCA from the four sce­nar­ios exam­ined (“stan­dard” and “future” ener­gy demand and “ÖKOBAUDAT” data­base vs. “EPDs”) show that the use of spe­cif­ic EPD data in the “stan­dard” ener­gy require­ment sce­nario results in an envi­ron­men­tal impact that is approx­i­mate­ly 3–5% low­er on average.
In the “future” ener­gy stan­dard, this effect increas­es to around 5–7% depend­ing on the envi­ron­men­tal impact con­sid­ered, due to the reduced influ­ence of the util­i­sa­tion phase (Fig. 2a).
Dr. Johannes Gant­ner explains: “The poten­tial for opti­mi­sa­tion through the use of spe­cif­ic EPDs is due in par­tic­u­lar to the high impact of the pro­duc­tion phase (see Fig. 2b). There­fore as the net ener­gy require­ments of build­ings decreas­es, the use of prod­ucts with spe­cif­ic EPDs pays off even more”.

Eval­u­a­tion of LCA results accord­ing to the DGNB

In addi­tion to cal­cu­lat­ing the build­ing life cycle assess­ments, the authors also addressed the ques­tion of how replac­ing gener­ic data with EPD data would affect the assess­ment with­in the build­ing cer­ti­fi­ca­tion based on the eval­u­a­tion sys­tem devel­oped by the Ger­man Sus­tain­able Build­ing Coun­cil (DGNB). For this pur­pose, they deter­mined the DGNB scores of the indi­vid­ual envi­ron­men­tal indi­ca­tors for the rel­e­vant LCA cri­te­ria. Depend­ing on the envi­ron­men­tal impact con­sid­ered, the use of spe­cif­ic EPD data in the “stan­dard” sce­nario results in an approx. 4–15% high­er score for the check list points (Fig. 3).

In the “future” sce­nario, swap­ping the data base for the life cycle assess­ment has a less­er impact. Due to the ener­gy-effi­cient con­struc­tion, best rat­ings that are close to the DGNB tar­get val­ues can also be achieved in this sce­nario using gener­ic aver­age data. How­ev­er, it is impor­tant to con­sid­er that the DGNB in turn is plac­ing increas­ing­ly high demands on the ener­gy effi­cien­cy of build­ings. If the bench­mark were to be adjust­ed in the future, the LCA data used would have a greater impact again, even for build­ings with a future-ori­ent­ed ener­gy standard.

Hans Peters, Chair­man of the IBU Board, is sat­is­fied with the results: “The study clear­ly demon­strat­ed that the use of spe­cif­ic EPDs in build­ing life cycle assess­ments is worth­while. The devel­op­ments in the field of ener­gy-effi­cient con­struc­tion will lead to the pos­i­tive effects of the use of EPDs – which are already clear­ly vis­i­ble – increas­ing yet fur­ther in the future. This sends an impor­tant sig­nal to our mem­bers and all those inter­est­ed in construction”.

The com­plete study (in Ger­man lan­guage) can be down­loaded here .