Mahsa Taslimi Niak – Saba Modaresi Alam – Mana Nemati Aghdam
- Maximizing south-oriented surfaces and inclined roofs during volume design
- Optimizing the glazing system by increasing the glazing to floor area ratio
- Implementing a shading system
- Adding skylights on the rooftop
- Using automatic roller blinds for all glazing parts
Daylight factors are calculated with VELUX Daylight Visualizer 3, a daylight simulation program based on CIE 16-1970 – “Daylight” and validated against CIE 171:2006 – “Test Cases to Assess the Accuracy of Lighting Computer Programs.”
Daylight factor levels in rooms are measured at work plane height (e.g. 0.85m above the floor), leaving a 0.5m border from the walls around the perimeter of the work plane.
In addition, to determine the glare potential, ASE calculations were done room by room.
The choice for all the windows was triple-glazed windows with 70% visible transmittance.
To mitigate glare potential, considering exterior roller blinds for the glazing parts, the openness factor and visible transmittance of blinds fabric were studied.
Corresponding to the radiation threshold, we selected blinds with 7.5% visible transmittance and 8% openness factor for the rooms facing south, and for the rooms facing north, we selected blinds with 38% visible transmittance and 40% openness factor since the glare potential in the rooms facing north was not as significant as the ones facing south.
The heat loss through the climate shell has been minimized using the best insulation solutions, reducing thermal bridges, and creating an airtight construction. The airtightness was tested just before completion.
The building uses a heat pump with pipes drilled 120m deep in the ground. The low-temperature floor heating and cooling can easily be adjusted by home automation. The supply of electricity is almost completely based on the renewable solar energy harvested by 72 PV panels on the roof of the adjacent barn.
The design of the load-bearing structure of the souterrain has been based on an expectation that the concrete structure will never be reused while being part of the Dutch dyke system. The steel structure on top could be disassembled and reused. The walls and roofs are made of wooden beams with insulation in between.
The outer surface is based on a durable corten steel structure that is ventilated and protected from direct rain, reducing the need for surface treatment. To minimize the use of water, a structure for use of rainwater for gardening was established.
THERMAL ENVIRONMENT STRATEGIES
- Thermal insulation
- Shading system
- Underfloor heating system
- Automatic thermal control system
Active Houses should minimize overheating in summer and optimize indoor temperatures in winter without unnecessary energy use.
Many examinations were done considering dynamic shading strategies which are adaptive to the radiation threshold.
When the rad is over 220 W/m² the shades are activated.
This strategy controls the heat gain and reduces overheating in summers.
A hybrid ventilation system was utilized: natural ventilation in summer and mechanical ventilation in winter.
The heating system is also scheduled: 12 hrs with a set temperature of 21°C which drops to a minimum value of 19°C during system shut-down.
The choices are related to the fact that the AH tool asks to meet requirements for a minimum of 95% of the occupied time, but it doesn’t consider some factors:
- An annual hourly evaluation does include the unoccupied hours which is more than 5% of yearly hours and to meet AH requirements these hours should be excluded.
- In bedrooms (especially at night-time) people are more sensitive to high temperatures when sleeping or trying to fall asleep, so in the reality, lower temperatures shall be eligible.
Basically, the temperature control strategy allows to reduces the influence of not occupied hours or night-time (when usually the heating system is not working) on the results and consequently on the scoring.
INDOOR AIR QUALITY STRATEGIES
- Natural ventilation by openable windows and window trickle ventilators
- Automatic roof windows
- Hybrid ventilation for cold seasons
The carbon dioxide concentration was studied room by room, and the number of users, and the schedule of use for each room, play an important role in CO2 concentration and were taken into account in our analysis.
The active strategies in general are described as the generation of electricity on-site through the use of high-efficiency photovoltaic panels that cover the roof. This system is able to optimize the production of electricity through renewable sources and the air-water heat pump, to provide heating and the production of domestic hot water.
38 Building Integrated Photovoltaic systems (BIPV) were proposed to be installed on the south-facing roof with a slope of 36 degrees as BIPV gives further opportunities for integrating the modules together with one or more roof windows.
The heat generator is made of a compact indoor unit, with two integrated 300-liter technical storage tanks (600 liters in total) for the production of instantaneous domestic hot water. An outdoor unit (air-water heat pump) with a nominal heating power of 16 kW (with COP equal to 3 for both DHW and heating), transfers heat from the outside air to the water supplied for heating by radiant floor panels with a dry installation system.
In general, annual energy consumption was divided into space heating, domestic hot water, lighting, and mechanical ventilation.
Here, the implementation of PV panels, with a total production of 27.8 kWh/m2 help the building achieve the NZEB standard, with a small quantity of energy that could be sold back to the local grid (8.4 kWh/m2).
The primary energy performance is equal to 8.4 [kWh/m2], obtained by the product of the total energy used for heating, DHW, lighting, and mechanical ventilation (19.4 [kWh/2]), to which the renewable energy supply is subtracted (27.8 [kWh/2]), per the national primary energy factors.
The structure used timber-based construction materials with a significantly lower embodied carbon (EC) value.
When modeled through life cycle assessment without relying on arguments about carbon storage, timber is indeed the lowest carbon option.
Furthermore, sustainable timber has the lowest embodied energy of any mainstream building material (energy used in processing, production, and transportation from tree to consumer usage), significantly less than steel, concrete, or aluminum.
The building’s LCA analysis determined the recycled content of 94 percent of the building’s weight for entire non-structural materials.
It indicates that chosen building materials, by being certified sources, lessen the environmental load (PEFC and FSC for wood sourcing, and EPD for other materials).
With gutters put on the roof surface, filtration, system tank, pumps, and treatment system, rainwater is collected to cover landscape irrigation, wash applications, and toilet and urinal flushing.
In order to save 167,310 liters per year calculated based on the roof surface and the annual rainfall, the capacity of the rainwater tank is determined.
Supplied water by a rainwater collection system will irrigate Tower Farms in the greenhouse, which uses closed-loop technology to recycle water and nutrients while consuming up to 98 percent less water than traditional farms.