The first findings from construction
Office centrum – building in the standard of 2020 – commencement – 10/2015, termination – 05/2016
- cooperation 7.2 kWp photovoltaic power system with 26kWh house battery and smart grid
- anticipated annual energy consumption according to UCEEB:
18–27 000 kWh - anticipated production of photovoltaic power system according to the supplier:
6 773 kWh - covering of consumption by own production of photovoltaic power system:
25–38 % - assumed possible time of autonomous operation of the building:
4–8 hod/24 hod
Setting of the building parameters was carried out under technical supervision of UCEEB ČVUT. ČEZ – ESCO participates in the project as the supplier of photovoltaic power system and battery storage. All the following decisive environmental parameters will be monitored complexly in all the operational regimes of the building. The following central offices delegated their experts into the work group:
- Ministry of Industry and Trade
- Ministry of the Environment
- Energy Regulatory Office
Quality of environment in nZEB
The measurements carried out at the laboratories of UCEEB ČVUT revealed that the selected type of the heating system is very important even in these extremely energy efficient buildings!
Vertical distribution of the steady-state temperature field (outside temperature -20 °C)
- floor heating Fig. No. 1 (temperature difference of 0.5 °C)
- wall under-window convector Fig. No. 2 (temperature difference of 3.6 °C)
Optimizing costs during preparation and construction
Individual constructions were chosen in cooperation with UCEEB so that they comply with the requirements for nZEB as a whole, so different variants for their individual constructions were processed. Then the cost analysis of individual variants with the aim of finding out the most economic solution was done:
Legislative requirements for the energy performance indicators:
| Requirements for the energy performance indicators |
new ADM after 1st January 2015 |
ADM in the nZEB regime |
|---|---|---|
| Uem,R | 0.37 | 0.33 |
| Qfuel (kWh) | 28 117 | 26 419 |
| QnPE (kWh) | 59 414 | 56 923 |
Selected variant of the building:
| Outer wall | Floor | Roof | Windows | ||
|---|---|---|---|---|---|
| U | U | U | U | g | Uem |
| 0.11 | 0.24 | 0.14 | 0.72 | 0.63 | 0.236 |
Assessment and classification of the Energy Performance Indicators
The course of overall non-renewable primary energy depending on the building envelope – building with a hybrid photovoltaic system.
Assessment of energy performance of the building – Energy Performance Certificate of the Building
Total investment cost of the building
| Enclosed area | 1 750 m3 |
| Total cost (excluding photovoltaic power system and batteries) | 13 642 tis. CZK |
| Cost per m3 | 7 795 CZK/m3 |
| Total cost (including photovoltaic power system and batteries) | 14 959 tis. CZK |
| Cost per m3 | 8 548 m3 |
| Current standard cost in ordinary buildings of the same purpose (CS ÚRS) | 7 700–8 300 CZK/m3 |
The first very interesting finding was the fact that this building, by its solution a very above-standard building, can be, in case of careful project preparation, built at the costs relevant to common buildings nowadays!
It is a fully electrified building where no other energy source than electrical energy is used. Heating is provided by the FENIX electric radiant systems with individual management of individual spaces, decentralized warming of non-potable water by small accumulative reservoirs in the place of consumption; controlled ventilation with recovery and multi-split unit for separate cooling of each space is for granted.
The selected system is very flexible and allows solving of even very small deliveries of heat or cold individually and without loses as immediately needed. For comparing, the supplier ensuring also deliveries of warm water systems with the air-water heat pumps was asked to process an offer for this alternative system used for delivery of heat, warming of non-potable water and for cooling of given spaces. For the sake of completeness, it must be added that the systems using water as the heat or cold carrier are, in similar buildings, significantly less flexible than the designed solution, thus they provide significantly lower comfort than the selected variant.
Comparing the systems – return of investment
(comparing the selected system and heat pump):
| The system of convector heaters 9 kW – large-area radiant heating – radiant panels – central regulation with possible remote control regulating each space separately | 174 thousand CZK |
| Multi-split air conditioning 11 kW + warm nonpotable water (3 kW), accurately and flexibly controlled deliveries of heat and cold to requested spaces | 193 thousand CZK |
| Heat pump and warm water system – inertia in hours – low dynamics, impact on other unintended spaces too | 661 thousand CZK |
| Difference | 294 thousand CZK |
| Overall energy consumption for heating and warm non-potable water | 9 335 kWh/year |
| Maximum possible savings when using heat pump | 4 700 kWh/year |
| Return of the investment to heat pump (current price) | 28 year |
The pay-back period of the heat pump is high above its service life and installation of the heat pump into similar spaces makes no economic sense!
In Jeseník, on 31st July 2016
Ing. Cyril Svozil
