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Owned by the Royal Dutch Navy, the Albatros building was formerly accommodation barracks for naval officers. The Navy was intent on demolishing it and starting again to create an office building, but life cycle analysis showed that the most cost-effective way of gaining the required office space was to strip and refurbish the existing building - using green architecture to renovate it into a green building. The building consists of a high-rise block (7 storeys, total of 4400 m²) with meeting rooms on the lower floors (1 layer, 1800 m²). The existing building was built in 1972 with an east-west, façade and is equipped with single glazing in aluminum frames, no insulation, inefficient artificial lighting, heating by radiators (gas boilers) and a mechanical ventilation system (supply & exhaust) without heat recovery. Objectives - 30 percent reduction in energy demand compared with current new build regulations - Any over-cost of eco-refurbishment to be minimized - Internal conditions satisfying all new-build criteria - High overall environmental assessment achieved
The choice of the measures was supported by an environmental assessment with a life-cycle analysis (LCA). LCA gives the possibility to define the environmental impact of different scenarios for the future of the building.
The existing building was heated by gas furnace and had no insulation, single glazed windows and inefficient artificial lighting. Refurbishing the existing building envelope would have been prohibitively expensive. Therefore, a new, second skin was installed over the existing façade. The steel construction was replaced with an aluminium frame. The old façade was made air tight and the openings replaced with airtight windows.
The second skin significantly improves the overall thermal quality of the façade by preheating ventilation air and removing the existing thermal bridges. Unwanted sound transmission to neighbouring offices through the air cavity between the facades is minimised by installing noise absorbing material at the ceiling of the cavity.
Solar Gain Control and Glazing
A sun shading device was mounted in the cavity of the second skin. This is controlled automatically but has a manual override.
The building is narrow with good day lighting and all desks are adjacent to windows. Energy efficient lighting with daylight dimmers and motion detectors were installed to reduce the electricity demand for lighting
Heating and Cooling
The Albatros building is fortunately located adjacent to an existing CHP system. The building was connected to this heat source through a district heating system, in order to make use of waste heat from the CHP plant. The existing convectors could not be re-used therefore new radiators were installed for heating in the offices.
In summer, night ventilation is used to pre-cool the thermal mass of the building. The uncovered, concrete ceilings enhance the exposed thermal mass, contributing to comfortable indoor conditions.
A good indoor climate has been achieved with passive measures. The building is naturally ventilated with new and larger, openable windows and special insulation behind the convector to avoid energy losses. Floor level ventilation inlets and ceiling level ventilation outlets were created along the full length of the façade; these are open in summer and closed in winter, when simple vents are used. The Coanda effect is utilised, so fresh air sticks to the ceiling panel where it mixes with room air before reaching occupant level. Waste air is mechanically removed from the building, using ducts and energy-efficient fans to decrease the use of electric energy.
The openings in the façade will be upgraded and the glazing in the new windows is LE glazing (U=1.8 W/m2K)
Insulation of closed walls, roofs and floors (U=0.3W/m2K)
A second skin to create a double façade to improve the thermal insulation and internal conditions and preheating of ventilation air during winter conditions
Passive ventilation system with wind independent ventilation vents with the possibility of night ventilation to cool the building mass in summer
Efficient heat delivery system from CHP plant on the Navy site.
Low temperature heating system
Efficient HF-lighting system with daylight dependent lighting
Photovoltaics: The architect is studying for a place for 100 m2 PV. The most relevant place is the south facade. PV can be combined with the outside insulation of the building.
The building phase was completed in September 2006 and in October 2006 the Head of the Royal Dutch Navy moved to the completed building. The Navy is very proud on the building.
During construction, it was discovered that the specification did not show a horizontal partition between floors in the second skin façade. This partition was essential in reducing overheating by preventing warm air from lower floors from rising to the higher floors. However, the partition was installed before the construction work was finished.
In the commissioning period, it became apparent that there were problems with the operation of the second skin façade. The ventilation grills were not airtight and a mechanical defect meant that they did not close completely in the winter period as designed, resulting in lower temperatures caused by the extra ventilation in the second skin façade. In addition to this, the BEMS controlling the operation of the grills was set up incorrectly. This caused the building occupants to feel cold during the winter, and meant that there was an unwanted noise in the façade when the high air flow moved along the ventilation holes.
To reduce the number of complaints about the temperature, the night setback mechanism was removed. The mechanical problems with the grills have now been resolved and the BEMS adjusted to the correct settings. The supplier have assured the WP 8 contractor that the air tightness meets design standards, however this is still under question and there will be discussion on this issue beyond the end of the REVIVAL project. It is intended that the night setback will be introduced when the problem is resolved.
Although some minor problems occurred in the first months, the first experiences of the users are good. Problems that occurred in the first month had all to do with the double skin façade. During windy conditions there was a lot of noise in the building. There were three causes for that problem. There were little holes in open metal constructions. They work as an organ pipe when the air strikes along the little holes. Closing the holes was the answer. The other problem was that the big grills for summer ventilation didn’t close. That problem is also fixed. The air in the double façade is much warmer now, and the wind doesn’t have much effect on the pressure drop over the windows between the offices and the double façade. Last problem was the air tightness of the new open able windows. The construction firm will look after this problem.