With free cooling systems, the cooling needs are reduced so the energy consumption is lower, and this is translated to a lower emission factor due to energy savings in a system that has 
Free cooling systems are in fact really simple, it allows the reduction of the internal air temperature without needing compressor systems or heat exchangers, so it results in the improvement of the air quality with fresh outdoor air and without noise pollution due to not having any "mechanical moving parts" and also integrating an effective sound attenuation system to improve the quality of life.
Great applications in spaces where the cooling demand implies a great consumption, like for example data centers.

It can be applied in air-conditioning systems (HVACs), with or without heat pumps, or photovoltaics.

Climate and geography:

Freecooling depends on the outside air temperature that must be lower than desired temperature, so it’s better suitable for climates with a large difference between minimum and maximum daily temperatures, or diurnal swing. For humid climates it has to be considered the increase in the humidity levels inside the building, which could reduce thermal comfort or even lead to mold growth (ATECYR, 2012).

Technical aspects/ infrastructure:

The system depends on the outside temperature, so will achieve greater efficiencies during cold seasons (100% freecooling) and during mid-season when the air will be partially cooled by the compressor. As shown in the figure below. The system is more suitable for locals with higher full load hours as industries, data centers, or even restaurants that have a yearly constant cooling load.

Figure 1: Freecooling capacity. Source: Airdale

This equipment has easy maintenance based on replacing the air filters, and is focused on avoiding microbial growth over dirty filters or stagnant water in drain pans.

Policy and regulatory/legal framework:

Freecooling is included as best practice in The Code of Conduct for Data Centres, a voluntary initiative managed by the JRC to reduce energy consumption. It also appears as a solution in the EPBD in order to increase the liveability of enclosed spaces.

Project governance and implementation modalities:

This technology has been included in European projects and national regulation due to the high impact of the space cooling needs, according to (IEA, 2018) air-conditioning accounted for nearly 20% of the total electricity demand in buildings worldwide and will almost triple by 2050. Some examples are Building Energy Codes, Minimum Energy Performance Standards (MEPS) and labelling.

Climate and geography:

It is not suitable for every location, the humidity must be considered, also in humid regions an enthalpy controller is needed to reduce measurement errors, which requires a higher investment and higher maintenance requirements. Enthalpy controllers include a thermostat and humidity sensor and help achieve greater savings (10-20%) compared to standard thermostats (ATECYR, 2012).

Other specific considerations regarding the temperatures of operation are that the system can become economically unfeasible when the heat exchanger works in range with very low temperature differences and that in cold climates, in order to avoid freezing onto the evaporator surfaces, the air ventilation shafts set-point temperature must be equal or greater than 5°C (ReUseHeat, 2022).

Policy and regulatory/legal framework:

Current planned policies to increase the access to cooling systems would have limited effect, the access to cooling systems can be targeted as a social issue and used only by 8% of the people living in warm regions.

This solution requires coordination with national governments to be properly enforced alongside with incentives it is needed the share of expertise and knowledge. Policies could integrate a local approach, where investment decisions are taken and implemented; to increase their effectiveness (IEA, 2018).

Project governance and implementation modalities:

Even if there is growing interest in programmes to increase energy efficiency in the building sector, efficient technologies and retrofitting measures are expensive. The economic viability of these measures, especially for renovating existing buildings; is strongly dependent of the inherent inefficiencies (IEA, 2018).

In humid climates it will need more maintenance and a de-humifier to reduce the humidity content and avoid mold growth (NANOCOOL, 2016).

• https://www.nortekair.com/wp-content/uploads/2017/01/Free-Cooling-Concepts-for-Data-Centers.pdf
• https://e3p.jrc.ec.europa.eu/file/2148/download?token=fOQRkXC6
• https://www.idae.es/uploads/documentos/documentos_09_Guia_tecnica_ahorro_y_recuperacion_de_energia_en_instalaciones_de_climatizacion_dd65072a.pdf
• https://blog.passivehouse-international.org/summer-comfort-passive-house/

Energy savings:

The pre-cooling of the inlet air can reduce the compressor operation, depending the outside temperature it can partly operate or even not been operated at all. This means a reduction in the energy consumption and a reduction of GHG emissions an energy cost. On data centers some freecoolers have shown energy savings up to 70 % versus conventional mechanical refrigeration (Nortek, 2015).

Health:

Freecooling systems improve Internal Air Quality (IAQ) thanks to the renovation with oxygenated fresh air and control of the humidity content, avoiding the so-known “Sick Building Syndrome” (NANOCOOL, 2016).

Thermal comfort:

The use of free-cooling systems reduces the operation of conventional compression air conditioning systems, which match the latent cooling loads by reaching the dew point of air. So, with conventional cooling systems sometimes the outlet air is too low for thermal comfort and needs to be re-heated, increasing even more the energy consumption (NANOCOOL, 2016)

DNSH:

Climate change mitigation

This activity leads to a significant greenhouse gas emission reduction on a lifecycle basis

Climate change adaptation

This activity will be more necessary for the liveability of future urban scenarios based on the forecasted future climate crisis.

Pollution prevention and control

This activity leads to a reduction of electricity consumption, and consequently to a reduction of emissions

• Governance EU Climate Neutrality Framework: https://netzerocities.app/resource-1728
• Loans for Energy Efficiency (EE) could include this solution as a way for improving EE in buildings https://netzerocities.app/resource-1648 . Same applies to Blended finance for Energy Efficiency (EE) https://netzerocities.app/resource-1658
• Building Renovation Passport (BRP) could include this solution as example. https://netzerocities.app/resource-1748
• One-stop-shop for building renovation  https://netzerocities.app/resource-1913
• User Engagement for Energy Performance Improvement  https://netzerocities.app/resource-1498

BODENTYPEDC data center prototype in Sweden (2019).

Data centers are characterised for having a high and constant cooling consumption, to evacuate the excess heat produced by the computers. In this prototype there is a freecooling coupled with an evaporative cooling system, to reduce the overall consumption. In Northern Europe evaporative cooling can provide temperatures below 25˚C all year round and achieve 99.9% ASHRAE Class 1 compliancy.

Integrated heating, ventilation and natural air conditioning in an office building

An office building was refurbished and now applies natural air conditioning principles, supplying and distributing the air through the cavities of the hollow floor instead of the existing air ducts. Now performs freecooling on summer nights, letting the fresh air into the building and refreshing the concrete floor; and even (air) floor heating in winter with heat recovery from the warm air rejected during the cold season.

CommONEnergy demosite in Mercado del Val, Valladolid (SP)

This historic marketplace was refurbished and included passive measures to increase energy efficiency. The system includes three reversible ground to water geothermal heat pumps (for DHW and cooling in summer) and also an Air Handling Unit (AHU), which can operate in free-cooling mode and with a heat recovery efficiency of more than 65%. The cooling production for all the markets is centralised, and the exhaust heat produced on the heat exchanger, is recovered for pre-heating the water circuit for space heating in winter.

With the refurbishment and installation of efficient lightings and HVAC equipment, savings on final energy are 75%, being lighting and cooling the ones with higher savings, both above 80%.