Ajimez slatted lattice solaria and ventilation screens represent the sophisticated microclimate-control systems of traditional Canarian domestic architecture. Adapted from Islamic Mudéjar traditions of southern Spain, the 'ajimez' is a twin-arched window opening divided by a central wooden mullion (parteluz) and enclosed with sliding or hinged wooden lattice screens (celosías). These screens harness the northeast trade winds (alisios) through the Venturi effect, lowering interior temperatures, blocking solar glare, and providing total domestic privacy.
At a Glance: Key Takeaways
- Architectural Feature: Ajimez (twin-arched mullioned window with parteluz column)
- Screening Technology: Celosías (interlocking diagonal or orthogonal slatted wooden lattices)
- Microclimate Mechanism: Passive evaporative and convective cooling via the Venturi effect
- Cultural Heritage: Andalusian Mudéjar and North African Mashrabiya lineage
- Thermal Performance: Reduces interior solar heat gain by 60%–75% while maintaining 100% airflow
The Mudéjar Inheritance: From Al-Andalus to the Atlantic
When Spanish master carpenters settled in the Canary Islands following the fifteenth-century conquest, they carried with them the refined architectural memory of Moorish Andalusia. Among the most brilliant manifestations of this legacy is the ajimez—a twin-arched window opening divided by a slender central column (parteluz) and enclosed with delicate wooden lattice screens known as celosías. In towns like San Cristóbal de La Laguna (a UNESCO World Heritage site) and La Orotava, the ajimez became a signature element of noble and ecclesiastical facades.
The term ajimez derives from the Arabic al-shamīs (meaning 'the sun-catcher' or projecting window). Rather than being a flat, utilitarian opening, the Canarian ajimez was designed as an integrated climatic and social filter. It synthesized Moorish timbercraft with Atlantic vernacular building methods, providing a dignified architectural face to the street while fostering an intimate, sheltered domestic realm within.
Geometry and Joinery of the Celosía Lattice
The core technological element of the ajimez is the celosía—an intricate, openwork timber lattice crafted from seasoned pino tea. Unlike crude modern lattice fences assembled with metal staples or nails, historic Canarian celosías were manufactured through precision joinery. Carpenters planed long, slender laths (listones) to exact dimensions, typically 6 millimeters thick by 18 millimeters wide.
Using specialized indexing jigs, artisans cut matching half-lap notches (ensambles a media madera) along the laths at a 45-degree diagonal or 90-degree orthogonal angle. When pressed together, the opposing laths interlocked seamlessly, forming a self-bracing, perfectly planar geometric mesh. The laths were encased within grooved perimeter frames (bastidores) that slid smoothly along waxed wooden tracks embedded in the window sills and lintels, allowing residents to adjust the opening with a gentle touch.
Thermodynamics of Passive Cooling: The Venturi Effect
The ajimez is an extraordinary example of pre-industrial passive climate engineering. The Canary Islands are swept year-round by the humid, steady northeast trade winds (los alisios). When these breezes strike a building facade fitted with an ajimez, the air is forced through the hundreds of narrow diamond apertures of the celosía.
This physical restriction accelerates the air velocity through the Venturi effect. As the air speeds up, its pressure drops slightly, inducing a noticeable evaporative cooling sensation on human skin. Furthermore, the wooden slats block up to 75% of direct solar radiation, preventing the scorching midday sun from heating interior stone floors and walls. The air inside the projecting solana remains dense and cool, sinking into the room and displacing warmer air, which escapes through high-level ceiling vents or open interior courtyard corridors.
Canarian Solar Shading & Ventilation Screen Typologies
Use this reference table to calculate exact physical dimensions, ratios, and specifications before purchasing:
| Screen Type | Lath Geometry | Airflow Capacity | Visual Privacy Level | Thermal Shading Efficiency |
|---|---|---|---|---|
| Celosía Diagonal (Diamond) | 45° criss-cross half-lap slats | High (65% open area) | High (opaque at oblique angles) | Exceptional (blocks direct midday sun) |
| Celosía Rectangular (Grid) | 90° orthogonal square grid | Very High (75% open area) | Moderate (direct sightlines inward) | High (blocks high-angle sun) |
| Persiana de Tablillas (Louvered) | Horizontal angled louvers | Moderate (adjustable) | Total privacy from street level | Maximum (complete solar block) |
| Postigo Ciego (Solid Panel) | Solid tongue-and-groove pine | Zero (closed) | Complete enclosure | High thermal insulation value |
Practical Constraints
Every successful decoration project must account for physical and environmental constraints:
Dust and Volcanic Calima Infiltration
Saharan dust storms (calima) blow fine particulate matter through open lattice screens into living areas. Mitigation: Incorporate operable interior solid wood shutters (contraventanas) that can be closed during calima events.
High Cumulative Surface Area Vulnerable to Weathering
The hundreds of linear meters of thin wooden laths in a single lattice screen accelerate oil oxidation and drying. Mitigation: Perform annual maintenance by wiping the lattice with a 70/30 mixture of boiled linseed oil and pure gum turpentine.
Execution Blueprint & Craftsmanship Sequence
Execute this professional sequence to achieve flawless results without backtracking:
Ajimez Frame Construction
Frame the outer window opening using heavy 100x150 mm pino tea jambs and lintel, carving a central rounded mullion post (parteluz) to divide the opening into twin arches.
Architrave and Horseshoe Arch Detailing
Carve twin Mudéjar-inspired rounded or slightly pointed horseshoe arch heads, fitting them into the upper frame to crown each window bay.
Lattice Lath Milling
Rip seasoned pino tea heartwood into hundreds of identical laths measuring 6 mm thick by 18 mm wide, planing all four surfaces to a silky smooth finish.
Half-Lap Index Notching
Clamp stacks of laths into a 45-degree angle jig and cut half-lap notches (3 mm deep by 18 mm wide) spaced exactly 35 mm apart along their entire length.
Lattice Screen Weaving and Assembly
Interlock the opposing diagonal laths at their notched intersections, tapping them home with a wooden mallet to form a rigid, self-bracing diamond celosía sheet.
Sliding Sash Framing
Mortise a lightweight pine perimeter frame around the cut lattice panel, ploughing a continuous 10-mm groove around the inner edge to encase the lath ends.
Track Installation in Solaria
Cut dual sliding tracks in the window sill and lintel soffit, waxing the wooden runners with beeswax to allow the lattice panels to slide open effortlessly.
Interior Shutters and Finishing
Hang interior solid pine storm shutters on hand-wrought iron pintle hinges, and saturate the entire assembly with warm linseed oil.
Common Mistakes & Countermeasures
Avoid these costly errors that compromise aesthetics, ergonomics, and budget:
Nailing lattice laths together with wire brads instead of half-lap inter-notching
Using wide laths with narrow air apertures
Installing modern clear window glass behind the historic celosía lattice
Project Execution Checklist
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Frequently Asked Questions
How does the Canarian ajimez differ from the traditional Arabic mashrabiya?
While both share a common ancestry in Islamic climate-responsive architecture, the Middle Eastern mashrabiya is typically composed of thousands of turned wooden bobbins fitted together without glue. The Canarian ajimez and celosía, influenced by Iberian Mudéjar carpentry, utilizes flat, interlocking half-lap wooden laths arranged in crisp diagonal or orthogonal grids, creating a lighter, more streamlined geometric screen.
What is the optical principle behind the privacy of a celosía screen?
The celosía operates on the optical contrast of daylight levels. During the day, the exterior street is brightly illuminated by Atlantic sunlight, while the interior room is in soft, cool shadow. A person inside the dark room can see outward through the open apertures clearly, but a person on the bright street looking inward only perceives the reflective sunlit surface of the wooden laths.
How do ajimez screens contribute to whole-house stack ventilation?
In a traditional two-story Canarian courtyard house, cool marine trade winds enter the building through the lower laths of the street-facing ajimeces. As the air absorbs heat from the living spaces, it becomes buoyant and rises, escaping through high louvers in the central roof lantern (lucernario) or open courtyard corridors. This continuous thermal siphon draws fresh, filtered air through the home without mechanical fans.
Why is the central column of an ajimez called a 'parteluz'?
The word 'parteluz' literally translates to 'light-splitter' or 'light divider' (equivalent to the architectural mullion). In medieval and Renaissance Spanish architecture, it refers to the slender stone or wooden pillar that divides a wide window or doorway into two distinct, harmonious bays, evenly distributing structural header loads while framing the twin light openings.
Social Optics: Privacy, Surveillance, and the Shaded Gaze
Beyond its thermal performance, the ajimez fulfilled a vital sociological function in traditional Spanish colonial society. In the patriarchal culture of the sixteenth through nineteenth centuries, the public street was predominantly a masculine sphere, while women of noble and wealthy merchant families occupied the private domestic interior. The ajimez provided a socially acceptable threshold between these two worlds.
The physical principle of differential lighting enabled a one-way visual filter. From the brightly sunlit exterior street, the dark interior of the room appeared completely opaque through the dense lattice, protecting the women of the household from public gaze. Conversely, looking out from the cool, shaded interior, the thin wooden laths seemed to dissolve, allowing residents to observe street processions, civic celebrations, and daily neighborhood life in total anonymity—an architectural gaze immortalized in Canarian literature and folk memory.