QUBIX 4 Prague – CASE STUDY
The successful reconstruction of an office building with a LEED® Platinum sustainable certification
The Qubix 4 project is the reconstruction of an office building
dating from 1976 into a modern, contemporary office building
meeting the highest requirements of the current market.
In May of 2012 the S + B Gruppe successfully completed the
extensive renovation of the building under the design of
Austrian architectural studio Ernst Hoffman, led by architect
Martin Tröthana. The building was Precertified Gold in LEED
Core & Shell in 2011, and certified as LEED Platinum in the
LEED 2009 Core & Shell system in December 2012.
Qubix 4 is located in Prague 4 between Na Pankráci, Štětkova,
and Na Bitevní Pláni streets. The building has seven floors
above grade and one underground floor, which serves as a
garage and for technological services. The ground floor is
designed to include restaurants and shops, while the upper
floors have an office function.
Comparison of energy consumption between
QUBIX 4 & Baseline building [kWh/year]
500000
450000
KEY PROJECT INFORMATION
(areas taken from the energy model)
- Total floor area of 13,637 m2
- Office 8,186 m2, 690 occupants
Conference rooms and assembly
areas 438 m2, 110 occ.
- Multi-purpose leasable area
1,306 m2, 183 occ.
- Other 3,707 m2,
Completed in 2012
2012 rental space occupancy ~70%
Special awards:
- LEED 2009 C&S Platinum
Building of the Year 2012
Best of Realty 2012
The renovation’s new facade is partially glazed with strip windows, with a total facade glazing ratio of
58%. The internal block courtyard facade (the south side of the building) is equipped with automatic
sunblinds. Additionally the facade spandrels and roof are exceptionally well insulated.
Securing LEED certification of the building:
400000
OPTIMAL Engineering was the Investor’s primary partner to ensure the
certification of the building and to oversee the full provision of services related
to LEED certification. For this purpose OPTIMAL partnered with Gardiner &
Theobald, and with their collaboration led the entire certification process to its
successful completion. Within the scope of the LEED certification OPTIMAL
Engineering solved all MEP design services; ex., from energy modeling,
through calculations of the microclimatic environment, ventilation volumes,
sanitary water demands, to the use of rainwater. With the principle of
certification came the primary project comparison with the American ASHRAE technical standard
(comparing the designed project with the American standard practice) and the evaluation of efficiencies
against this baseline standard. OPTIMAL’s other services were then the approval of selected materials
and systems, comparing their performance and technical criteria with the minimum ASHRAE
requirements, and the technical supervision of the construction of the building.
350000
300000
250000
200000
150000
100000
50000
0
Baseline Building
Qubix 4
KEY FEATURES OF THE MEP SYSTEMS:
Ventilation:
- Air handling units with a heat recovery system for supply and
exhaust air from the offices
- Office air supply independent of the heating and cooling
system, induction supply units for conference rooms
- Variable air volume units in the conference rooms
Heating and cooling
- Gas condensing boiler heat source
- Heating and cooling of office spaces with radiant mats
embedded in the ceiling plaster layer
- Cooling with a pair of compressor chillers with dry coolers
and free cooling
- Ability to use waste heat from cooling to heat offices in the
transitional period
Sanitary system
- Low water consumption flow fixtures and fittings
- Local electric hot water heaters at the point of consumption
- Collection of rainwater from both roof and grounds for use
in flushing of toilets and urinals
Electrical Power and Lighting
Local automatic lighting control according to daylight
intensity and occupancy, using LED technologies
DESIGN AND REALIZATION TEAM
Investor: Plan & Bau CR s.r.o.
General Contractor: PP53, a.s.
MEP Contractor: Alpine-Energie Czech Co. s.r.o.
Design Architect: arch. Atelier Ernst Hoffmann, Vienna
Construction Design: M3M s.r.o.
MEP Design: OPTIMAL Engineering Co. s.r.o.
LEED MEP incl. energy modeling: OPTIMAL Engineering Co. s.r.o.
LEED certification: Gardiner & Theobald Co. s.r.o
In the framework of the evaluation of the energy performance of the building for LEED certification,
OPTIMAL Engineering worked on total energy models of the designed project and a reference
building constructed according to the ASHRAE standard; and then the simulation of the operation of
both buildings in the energy models. The goal was to compare the energy consumption and operating
costs of both buildings, and quantify the projected savings relative to the reference building,
reaching savings of 40.6% in energy and 24.1% in operational costs.
Use of energy modeling and technical support for the building design:
The integrated design of building systems, including the design of the final elements, was conducted
by OPTIMAL Engineering from the project’s beginning and was simulated with HAP 4.51 software,
according to the ASHRAE 90.1-2007 methodology (compatible with LEED 2009). This software was
also used to complete the whole building energy simulation, which enabled the development team
from the very first design draft to monitor the effects of design solutions on the final energy
consumption of the finished building. In this way the effects of individual variants were assessed and
precisely quantified: facade adjustments, use of different types of HVAC units, use of different types
of refrigeration equipment, terminal units, etc. Based on these simulations, the Investor could
therefore responsibly select which elements to use in the building, and assess their potential for
economic returns. The energy model was gradually modified and, after updating with respect to the
actually installed systems, was used to generate outputs for the LEED certification of the building.
Use of the energy model in building operations:
The LEED system continues to work with the building owner, even after beginning operations. In
the first stage the energy model results were used to determine the operating costs of the building
and helped the owner to determine the rental rate. OPTIMAL Engineering cooperated in putting the
building into operation and controlling the required settings of the installed technologies, and
continued to verify the actual parameters monitoring the operation of the building and the savings
achieved (i.e., the Measurement & Verification process). Preliminary results after a half-year of real
operations show compliance with the forecasted energy model to within 10% of actual
consumption.
MEP Project Engineer: Pavel Hosenseidl, Ing., ČKAIT
OPTIMAL Engineering spol. s r.o.,
Dělnická 12, Prague 7, tel: 222 994 400
www.optimalcompany.com
[email protected]
NOTE: The ‘LEED‘ Certification Mark is a registered trademark owned by the U.S. Green Building Council’ and is used with permission.