Slovenian architects OFIS Architekti shared with us this affordable sustainable housing project in El Paso, Texas.
The proposal separates the site in two roughly equal halves: North and South. The North is proposed for Phase II of the development, because its corner location suited best as commercial or mixed use development. Housing complex is located in more quiet, southern part of the plot and is gathered in a form of a nest – living mount of apartments, stuck one above another. The form makes a perfect shape as a shield protecting the units from sun and wind and the other hand offers quality environment: light, well ventilated with created different types of shared areas, both external and internal. Apartment units are orientated towards the internal park or towards the exterior. With its orientation keep intimacy and opened views to inhabitants. Apartments on level +1 around the internal park have atriums and terraces connected to the plaza.
Central garden
The roof of the garage on ground level creates internal park on the level +1. Apartments on the ground have own gardens and patios protected by sand mounts-lifted landscape creating fence and feeling of security and privacy. Apartments on level +1 around the internal park have atriums and terraces connected to the plaza. All other apartments have small loggias-shading devices with small space for plants.
Spaces between and around apartment units are shared spaces. The organization evokes communal diversed space. Some spaces are sunny and can be used on cold days; some are shaded and protected from the sun and wind. Some spaces are more intimate others opened and evoke communication. Some have views to the City or the mountains, others are enclosed. On the level 0 lies garden around the island with patterns of sand and desert vegetation. Topography of landscape is folded and creates intimate patios in front of ground apartments. Parts of level 0 are used for parking and loading.
Intimate Park
The roof of the parking on the ground level creates internal park on the level +1. Apartments on the ground have its own gardens and patios protected lifted landscape creating natural barrier and feeling of security and privacy. Apartments on level +1 around the internal park have atriums and terraces which are connected to the plaza. All other apartments have small loggias.
Access to the garage is from the South East. Here also external covered parking for visitors are located. Entrance for bicycle and bicycle storage is from the same level. All the rest of the site is for pedestrians only
Landscape design is inspired from natural environment around El Paso. It is combination of stones, sand and pebbles in different colours and textures. Plants selection does not need extra care and maintenance and it does not need artificial watering- combination of cactuses, palm trees and desert plants. Landscape creates flat areas as well as ramps and slopes. These artificial mounts create entrances to the plaza on level +1 or fences that offer intimacy of ground apartments and their gardens.
Living unit: space of intimacy, safety and protection
There are two types of living units: 52 one bedroom apartments and 14 two bedroom apartments. Apartments are repetitive and simple but when gathered together perform a unique enclosed unit.
All units are combined from repetitive elements and allow construction with prefabricated elements.
All bathrooms, closets, kitchen units, windows with shading devices are the same module.
Prefabrication and repetition
Housing units are repetitive rectangular containers made in horizontal and vertical grid with common dimensions. A repeated layout will be economical and facilitate faster construction. Construction systems and installation details are uncomplicated. Both, apartment units as well as its elements such as room sizes, kitchen, bathroom, window and door dimensions, closet assemblies, cabinets, ceiling and flooring materials are standardized and simplified. They can be prefabricated in a factory and installed on site. Stairs, columns, beams, elevator shafts, floor and wall panels, vertical shafts such as refuse chutes are precast elements. Structure is simple made of reinforced concrete with standardized beam and column sizes. Load-bearing walls are external apartment units divisions so at the same time produce effect of sustainability. All other elements inside the unit and common areas are non-load bearing walls so flexibility inside the units is possible.
Project consists of simple and repetitive units stuck together in a unique form. Complex is a living mount with shared areas between living units. Units are separated due to cooling effect and have shading devices. Different levels create rich external spaces and terraces that are occupied by shared facilities. Thick walls of living units that keep the right temperature inside the units have plaster and stucco. Shading system is made of precast wooden panels. Shading device is of textile that produces shade but anyway allows inhabitants to see through. Materials are durable, economical and easy to maintain.
Other Conceptual Issues
Important conceptual issue is to create a human friendly environment. Shared spaces are positioned and organized in a way that evokes friendship and dialog. The scheme provides a welcoming and adaptable living space for local families. Security is still a priority. Complex is easy to control and secure, nest organization evokes privacy and intimacy. On the other hand views, daylight, and cross ventilation is allowed.
The complex is higher on the north and lower on the south. Difference in levels creates terraces and living roof. These are spaces of diverse character and sizes. Space between apartment entrances is airy and bright covered space that creates loggia effect. These are small shared areas for dialog, rest and meetings that are used as semi private terrace. On top of the units roof terraces appear. Some are covered, some uncovered, and some are partly closed from the side. This creates different spaces that can be used in all weather condition. One can enjoy sun in the winter or be protected from it in hot summers. One can be protected from the strong wind but still enjoy external space that is ventilated and airy. On roof top we propose a gym and small spa that is closed. It can be extended to the terrace. We also propose spaces for barbecue and sun-terraces. Since the roof appears both, on top of level 3 or level 4 each unit has its roof terrace almost next to it. Roof of garage is an internal garden that is a special feature of the housing. This space creates its own intimate, green and friendly ambient. One fells safe and protected from the sun, wind, views from the road and surrounding.
Parking below the garden:
Locating most or all parking spaces under the communal garden serves a dual purpose. On one hand, it reduces the development footprint thus enhancing open space, minimizing the heat island effect and storm water runoff. This also contributes to the following LEED credits: (1) SS Credit 5.1: Site Development- Protect and Restore Habitat, (2) SS Credit 5.2: Maximize Open Space, (3) SS Credit 6: Storm water Management, and (4) SS Credit 7.1: Heat Island Effect – Nonroof. On the other hand, the garage space is used to draw air from the outside and channel it upwards through vertical chases to ventilate the buildings and create a passive heating / cooling effect. An angled drive connects the parking garage with Boone Street. There is some surface parking along the South side of the drive for visitors. The parking spaces will be covered. Pervious pavement is used for the drive which contributes to LEED SS Credit 6.1 Stormwater Design–Quantity Control. We are proposing to use shading devices on the East and West of the building to protect the units rom Summer Sun, while allowing the Winter sun to heat the units. Once the individual units a modeled the shading devices will be adjusted and optimized. Organisation of the nest evokes safety. All spaces and entrances can be easily secured and controlled.
The following is a basic outline specification of the major building components:
Reinforced concrete structure with each unit or group of units forming a concrete box. The goal is to keep the heat and heat generating elements on the outside of the box and take advantage of the concrete mass which retards the heat flow from the exterior to the interior during the day. The high volumetric heat capacity and thickness prevents the heat from reaching the inner surface. When temperatures fall at night, the walls re-radiate the heat back into the night sky. Thus it is important that all exterior walls have sufficient mass in order to prevent the ingress of heat into the interior.
LED, T-8 and T-5 light fixtures offer superb light and lower energy use. Motion sensors throughout the development help keep lights off when they are not needed. Structural system
The main drivers when choosing a suitable structural system for the building were quality assurance, simplicity, speed of construction and cost efficiency. Therefore the vertical structure, which resists gravity loads and horizontal forces (for example those resulting from wind action), was rationalised to precast reinforced concrete walls. Typical wall thickness will be 250 mm.
Precast wall system comprises two precast concrete plates that contain the specified amount of reinforcement. These two plates and are spaced apart and held together by lattice girders. Once the composite wall panels are delivered to site and erected in position, the gap between the plates is filled with structural concrete. The main advantages of this wall system are custom design, specific to the proposed architectural layout, high precision in-factory moulding and possibility of fair faced concrete finish on both sides. An alternative to this structural system is reinforced concrete frame, made of precast columns and beams, stiffened by staircase and elevator cores. Walls between different owners can be made of brick in this case, which offers greater comfort to the users. Interstorey slabs will be either cast in-situ or made of precast hollow core concrete elements. Strip and pad foundations are foreseen below walls and columns.
Design Techniques
Solar energy is the cleanest, most abundant, renewable energy source available. And the U.S. has some of the richest solar resources shining across the nation. Today’s technology allows us to capture this power in several ways giving the public and commercial entities flexible ways to employ both the heat and light of the sun.
The greatest challenge the U.S. solar market faces is scaling up production and distribution of solar energy technology to drive the price down to be on par with traditional fossil fuel sources. Solar energy can be produced on a distributed basis, called distributed generation, with equipment located on rooftops or on ground-mounted fixtures close to where the energy is used or on a large-scale concentrated basis in solar farms. There are four ways we harness solar energy: (1) photovoltaics (converting light to electricity), (2) heating and cooling systems (solar thermal), (3) concentrating solar power (utility scale), and (4) lighting. Active solar energy systems employ devices that convert the sun’s heat or light to another form of energy we use. Passive solar refers to special siting, design or building materials that take advantage of the sun’s position and availability to provide direct heating or lighting. Passive solar also considers the need for shading devices to protect buildings from excessive heat from the sun.
Solar thermal and PV devices are dependent on light, not heat – and this light does not need to be direct. Put another way, if you can find your way around outside, a solar panel could be working. The map below shows solar resources throughout the U.S. While the Southwest enjoys particularly good resources, the entire U.S. has adequate solar resources.
The map below shows the quality of U.S. solar resources compared to the two leading countries in solar energy, Germany and Spain. El Paso, having the highest energy density of any Texas site, is the ideal location for solar power generation capable of yielding 8,000 Megajoules of energy per square meter over the span of a year.
Parking, Loading & Storage
Entrance for the car is from the Boone Street on the position of existing Entrance. The access can be controlled wit an electric gate. Here external parking for visitors is located. Parking has a roof covered in photovoltaic cells and offers space for 22 cars. Garage for inhabitants is on the level +0. This is internal covered garage with natural ventilation. The roof of the garage creates a courtyard on level +1. By the entrance to the garage space for security and night guard is positioned. This position has good views to all the entrances to the area and control of parking and loading. Garage has space for 60 cars including for handicapped drivers. Garage is spacious, and due to its circular simple organization friendly to use . It is ventilated through the wide car entrance so it is sustainable , light and airy. From the garage there are easy entrances to the elevators, visitors hall and there is external ramp to approach to the plaza above the garage. By the garage entrance is also a bay that allows loading and storage. From here there is easy access to all areas and elevators.
Unlike single family residences in multi-family housing providing natural light to every room is often impractical and even impossible. Thus a typical apartment plan will contain rooms which are dark and require additional artificial light which increases the energy use of the building as well as creates heat from the light source which then increases the air-conditioning demand further increasing the energy use of the building. This compounding effect can be avoided by using innovative light collection systems on the facades and roof which collect sunlight and transport it deep inside buildings, north facing or even under ground rooms to replace heat generating conventional light fixtures.The sunlight is collected on the roof or exterior façade and channeled via optical cable to the interior of the building (current max. distance is 45 feet). Once inside the space the light is flows through luminaries specifically designed to recreate the feeling of sunlight. Not only does this result in a vibrant indoor environment and a shimmering sense of sunlight, but it also eliminates the heat gain from the conventional light fixtures since in our design the heat generating elements remain on the exterior, that is in the void between the two concrete slabs (see section diagrams). These light fixtures can also be used to enhance the light level and quality in north-facing rooms which do have windows, but because of their orientation real sunlight is lacking or the lighting levels are inadequate. The lenses located in the solar panel are designed to track the sun via a photosensors which do not require pre-programming. The actual movement is achieved via a low-consumption motor. The disadvantage of these fixtures is that the sunlight is instant and thus not capable of being stored. Thus, as the sun sets the light will diminish and completely disappear. Thus conventional light fixtures will have to be used at night.
project team:
OFIS Project Team: Rok Oman, Spela Videcnik, Janez Martincic, Katja Aljaz, Janja Del Linz, Andrej Gregoric, Katarzyna Bernatek, Robert Janez, Cristian Gheorghe
Mayse & Associates, Inc., Dallas, Texas / Dan Kazachki
Consultants: Sustainable engineering: Anthony Martin PE, LEED® AP / Henderson Engineers, Inc. , Dallas, Texas Structure engineering: Jaka Zevnik u.d.i.g., ELEA IC d.d., Ljubljana, Slovenia
