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ALTERNATIVE is a Paris based engineering consultancy company with expertise in acoustics and lighting design.
We are involved in architecture and urban design.
Our clients benefit from our experience of working on a wide range of projects in France as well as overseas.
PREPARATION PHASE

- Studies of user requirements, site conditions, planning, design and cost

- Defining criteria and targets to comply with regulatory requirements and specific needs

- Preparation of general outline of requirements

DESIGN PHASE

- Design review

- Criteria and detailed design reports

- Modeling and calculations

- Measurements

- Specifications

CONSTRUCTION PHASE

- Site visit

- Calculations

- Pre-completion testing

SUSTAINABILITY

Our engineers are suitably qualified under environmental guidance to carry out site assessments and provide advice on the maximization of acoustic and lighting credits :

- HQE

- H&E

- QUALITEL/CERQUAL

- BBC Energy

- BREEAM

- LEED

Our firm provides a methodological approach to acoustics and lighting design in order to ensure :
Functional building design
Adequate technical solutions based on guidelines and our experience
Design understanding
Technical and financial feasibility of the solutions
Technical solutions durability
A rational approach to sustainable development
A teamwork with architects and other engineers at all stages
Responsiveness and transparency

FOUNDERS

ALTERNATIVE was established in 2010 by two partners: Alexis Tremeau and Thomas Argence. They are both consultant engineers and have a Master degree in Acoustics and Lighting Engineering. They have previous work experience in prestigious Parisian agencies as well as in international ones (London and Tokyo).


OUR TEAM

ALTERNATIVE has now a dynamic, committed team with a musical and scientific expertise dedicated a wide range of project types. Our role as consultants brings us to rely on a constant dialogue with architects, set designers, digital and audiovisual technologies specialists, designers and artists.

MEMBERSHIP

IOA - Institute of Acoustics
IALD - International Association of Lighting Designer

MEASUREMENT INSTRUMENTS
Sound & vibration level meter Type 1 SVAN 957 and 958 SVANTEK
Sound level meter Type 1 Nor-140 NORSONIC
Accelerometer for measuring vibration WILCOXON
Portable PA loudspeaker JBL
Tapping machine Nor277 NORSONIC
Light level metre
SOFTWARES
Room acoustics consulting: CATT Acoustics
Environmental acoustics: AcouS PROPA
Building acoustics: Acoubat
Metrology NORSONIC, SVANTEK and 01dB
Lighting: Dialux, Radiance, IES
Lighting photo simulation: Photoshop
Building design faces many acoustic challenges and requires tailored solutions to be implemented in the project at the earliest stage.
The ongoing progress of construction requires technical and up-to-date knowledge but also building site experience.
Good design involves bespoke acoustic requirements in conjunction with sustainable solutions.
Airborne sound insulation

Airborne sound insulation is used to assess noise level difference both between adjacent rooms within the building (e.g. between offices, flats and music studios) and from external noise sources (e.g. road, rail and airplane noise).

The sound insulation between two rooms separated by a partition depends on the sound transmitted through the partition itself (laboratory acoustic rating Rw for Europe or STC for United States) but also on various other settings :

- The sound transmitted via flanking paths (through facades, technical ceilings and floors)
- Receiving room volume and reverberation time
- And workmanship issues such as gaps not fully filled, partition/slab junction not sealed well, wall linings not staggered

Based on our calculations and building site experience, ALTERNATIVE works with the project team to develop technical solutions ensuring sound insulation requirements are fulfilled.
Criteria :

- In-situ sound insulation rating : DnT,w (Europe) - FSTC (United States) - (dB)
- The higher is the value, the higher the sound insulation is

Impact sound insulation

Impact noise due to footsteps, dropped objects, scraping furniture or jumping children, can be a noise issue in contiguous rooms if the floor impact sound insulation performance is not appropriate. Therefore, energy due to impacts is transmitted through solid paths and is radiated by walls and floor constructions into noise in adjacent spaces.

To solve the problem, it is necessary to specify a concrete screed, a timber floating floor or a soft floor (e.g. carpet). Based on our experience, we give recommendations to ensure the floor build-up is appropriate and proper details have been taken into account in the design (e.g. acoustic underlay not bridged by service or skirting).

Rain noise can also be an issue. Impact noise of rain on skylights or glazed roofs can be really problematic (especially in restaurants, office spaces and classrooms).

Roof build-ups have to be selected (acoustic laminated glass) so rain noise is controlled.

Criteria :
- L’nTw (dB) for impact noise and Ln,e,w (en dB) for rain noise : The lower the value, the higher is the noise attenuation

Walking noise level

Floor finishes can often produce unpleasant loud noise and disturb work activities when walked on. This type of noise is heard in the same room (contrary to impact noise) and is referred to as walking noise.

Therefore, it is essential to have a specific care when selecting floor finishes.

Criteria :
- Walking noise index Ln,e,w (dB) : The lower the value, the lower is the noise in the room

Room acoustics

Public spaces (e.g. halls, restaurants, swimming pools, stadiums), working areas (e.g. offices, meeting rooms, open plan offices, classrooms), or auditoria (multi-purpose hall, concert halls, theatres), should be designed so reverberation is controlled. Absorptive materials and scattering elements can be used in order to do so.

Consequently, our role is to work together with the architect to select the adequate materials and define their integration in the space at the earliest stage in the project.

Key factors such as room volume and shape are aspects that have to be taken into consideration to avoid echoes (study of room dimension ratios, parallel surfaces) and uneven spectral responses (stationary waves, nodal modes).

Criteria :
- Reverberation time RT (seconds, s) : the lower the value, the driest is the room. The higher the value, the more reverberant is the room
- Attenuation by doubling distances A (decibel, dB) for big volumes as exhibit spaces or industrial halls : The higher the value, the driest is the room

HVAC noise

HVAC equipment such as air handling units (AHU), chillers, pumps, but also electrical gears such as transformers are potential noise sources that can disturb occupants in a building.

It is possible to distinguish two types of disturbances :
- Airborne noise levels due to HVAC units themselves (radiated sound from a AHU unit, high frequency noise from an electromagnetic ballast) or indirectly (ductwork regeneration noise)
- Structure-borne noise levels due to vibrations from HVAC equipments with rotating motors (Chillers, AHUs, Generators,…)

We assist HVAC engineers in the plant design and equipment specification to prevent high airborne noise levels. We also make sure plant rooms sound insulation (positioning and design) , ductwork attenuation (ductwork noise calculations, silencers design) and regenerated noise (e.g. coming from airflow through dampers and terminal grilles/diffuser) are controlled.

Structure-borne noise levels due to vibrations can be reduced with damping solutions to attenuate the energy transmitted from the equipment to the structure (anti-vibration mounts, padding).

Criteria :
- Sound pressure level LAeq and Leq (decibel, dB) : The higher the value, the noisiest it is in the room

Outdoor noise propagation

Plant noise is a potential source of noise disturbance for the nearest premises (e.g. roof plant such as generators and AHUs).

Thus, it is necessary to prevent those noise issues by designing solutions to attenuate noise so the project complies with regulations and local authority requirements.

To prevent and solve this issue, we carry out noise and vibration measurements, impact studies and calculations of outdoor noise levels around the site in activity.

We also use 3D modeling for noise mapping purposes.

Therefore we design technical solutions taking into account architectural and technical issues as well as economic aspects in the project. We carry out a noise assessment to ensure noise from the project will not create a future problem. Technical solutions usually take the form of acoustic screens, acoustic casing and attenuators.

Criteria :
- Sound pressure level Leq and Leq (dB) : The higher the value, the higher is the noise nuisance

Construction noise

Construction often generates community noise/vibration complaints.

Therefore, measures should be taken during the construction phase to mitigate noise and vibration.

For instance, ALTERNATIVE can give you recommendations on :
- Schedule of noisy activities with restricted times
- Noise specifications on construction equipment
- Alternative constructions methods
- Design temporary noise barriers

In addition, continue noise and vibration monitoring can help to assess noise levels and identify noise sources on site. It can also be used to define action levels to evaluate and take action to reduce the noise and vibration activity. It also contributes greatly to initiate discussion and arrangements between the parties (e.g. contractor and local residents).

Sound system
design of an enclosed or outdoor venue
Specific electro-acoustic system study
Even sound distribution
over the audience area
Other criteria
such as intelligibility
The success of a project depends on loud speakers

- Selection

- Number and positioning

- Sound power level

- Directivity and orientation

We base our approach on computer 3D modeling and experience to design sound systems and determine

- Accurate positioning of speakers

- Line-array enhancement

- Acoustic criteria mapping on the audience area

The electro-acoustic study of a room includes sound system design but also other acoustic matters such as
- Noise break-out issues It is crucial to make sure the sound insulation provided by the building envelope is suitable to comply with the local authority requirements. For instance, the facade build-up may have to be improved
- Noise exposure The sound pressure level in the venue may also require to be limited to avoid hearing damage due to harmful noise exposure
Noise disturbance for local residents
Building or infrastructure where noisy activity occurs (industrial site, entertainment or sport venue, railway infrastructure).
Noise and vibration assessment
We carry out noise and vibration measurements, impact studies and calculations of outdoor noise levels around the site in activity.
Additional studies
We also use 3D modeling for noise mapping purposes.
Meet the local authority requirements
We design technical solutions taking into account architectural and technical issues as well as economic aspects of the project and carry out pre-completion testing.
Auditoria should be designed so reverberation is controlled. Several acoustic criteria are used depending on the room type (multipurpose room, conference room, concert hall, classroom). Targets can be given for each criteria to ensure the acoustic is suitable for each purpose.
The acoustic quality of a room depends on room volume, shape and acoustic properties of materials.
SCHEMATIC DESIGN
Our first approach is based on 3 fundamentals :
Room volume (volume per seat m3/seat)
Reverberation time (seconds)
Study of early reflections towards the audience area (work on the room shape, positioning of sound reflectors, preliminary selection of absorptive materials)
DESIGN DEVELOPMENT
During the design stage, we undertake a specific study using 3D modeling and our acoustic software. Therefore we can :
Detect unwanted reflections or echoes
Adjust reverberation time
Ensure the sound diffusion in the room is controlled using criteria such as intelligibility (STI, RASTI, clarity), Lateral Energy Fraction (LF, LFC), strength (G)
OTHER ASPECTS :
The acoustic study of a room includes room acoustics but also other acoustic matters such as :
Airborne and impact sound insulation between adjacent spaces and the room. Noise break-in and noise break-out to the exterior environment
HVAC noise propagation to the room
The likelihood of complaints arises when vibrations from mechanical equipments, construction activities or transportation infrastructures are transmitted through the building construction and radiate as unacceptable noise and/or high level of vibrations in an occupied space.
Building vibrations are generally blamed for:
Disruptive vibration for occupants that affects work /sleep by felt vibration or radiated noise
Building structure damage
Perturbations of high-precision equipment (sensitive electronics, laboratory, and medical technology)
Artwork deteriorations
Vibrations sources are various and include :
Road and railway traffic (heavy trucks, freight trains, and also mass-transit and light-rail trains)
Operation of construction equipment (pile driving, demolition activity, blasting, crack-and-seat operations)
HVAC equipments (cooling towers, chillers, air handling units, pumps)
Nowadays, lightweight building constructions have replaced heavy constructions from the past. Plant rooms are generally located near sensitive areas due to valuable floor space. Fortunately, the path of the vibration can be readily cut off with properly designed vibration isolation.
ALTERNATIVE designs vibration isolation solutions to control and mitigate vibration generated by mechanical systems, equipment and machinery, transportation, industrial plants, and other sources.
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Criteria : :
Maximum rms acceleration La (dB re 1e-6m/s2), Peak Particle Velocity PPV, Vibration Dose Value VDV
Light is a major component of life on earth and it seems logical that natural light constitutes building's primary source of lighting. The light influences people’s lives and their way of living, therefore every building should be able to provide enough daylight not to interfere with the natural cycle of human beings.
Buildings orientation should be designed to facilitate daylight access to the occupants bearing in mind glare and overheating must be avoided (e.g. using louvers, overhangs or light shelves).
As a primary purpose, a window provides light to enable a building to function, as well as creating a pleasant visual environment that provides us with an important “feel – good” sensation.
The view through a window, or how we perceive the world outside, is a dynamic experience associated with changes in skylight, sunlight and season. At its lowest level, the view satisfies the physiological need of the eye for a change of focus, and provides an awareness of the environment beyond the building. The quality of the view is clearly of importance.
The size, the shape and the position of the window will have a direct effect on the view out, and the designer needs to be aware of that during the concept phase.
Our role is to make sure daylighting is part of the overall lighting design by considering luminaire layout, lighting circuit layout and lighting control strategy.
Lighting design is subject to a dichotomy of requirements, aesthetic dimension of architecture on one hand, and technical need of light on the other hand.
For us, the lighting scheme is an extension of the architectural design and should 'tell a story'.
We highly value the understanding of the building since its function and its constraints are the preludes of this story.
Our team works closely with the client and the project team, with the aim of producing a good lighting design.
Once an agreement on the design has been done and a main lighting scheme has emerged, we develop our work based on a technical approach :
Choosing the correct lamp
Choosing the right luminaire
Conceive the lighting layout
Achieve the correct light levels
Make sure of appropriate uniformity ratios
Glare control
Sustainability and low-energy awareness
Our range of services includes all artificial lighting aspects :
Interior
Lighting design of interior spaces. Ensure compliance with regulations and guidelines in addition to client requirements
Exterior
Lighting of building facades, monuments and various public venues (sports arenas, bridges,...)
Museums & Exhibitions
Temporary displays as well as permanent shows
Retail and commercial
Lighting concepts for brands and retailers, market analysis, creation of atmosphere
156 rue Oberkampf
75011 PARIS
Tel. : +33 (0)1 44 93 07 84
Fax : +33 (0)1 73 79 20 50
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Chaillot National Theatre - Paris
Conservatory - Saint-Paul
Dance school - Joinville-le-Pont
Maison de la Culture 'MC93' - Bobigny
Media Library - Epernon
Residential building Charolais - Paris
Social residences - Pierrefitte
Youth Hostel - Paris
ARTELIA Group offices - Choisy
Banks of France - La Courneuve
Group offices - Lille
Michelin RDI Campus - Cébazat
Offices - Clichy-la-Garenne
Thales headquarters - Carpe Diem tower - La Defense
Tour AREVA - Executive floor - La Defense
Anatole France school - Charenton-le-Pont
Eco Campus - Vitry
Orange Campus - Montrouge
Research and teaching center - Saint-Denis
Research laboratory - Orsay
School and gymnasium - Boulogne-Billancourt
Nursing Home - Montmorency
University Hospital Centre of Fort-de-France - Martinique
Football stadium - Lyon
Roland Garros - Historic Triangle - Paris
Sports complex - Issy-les-Moulineaux
Sports hall - Rezé
Swimming pool - Strasbourg
Cycle- and footbridge on Lake Leman - Geneva
Mixed-use development - Saclay
New Courthouse - Poitiers
Penthemont Abbey - Paris
Shopping Centre - Meaux
Supreme Court - Burundi
Viaduct and Metro station - Grand Paris
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