Dear All,

We are looking to bridge a contradiction between energy savings and comfort requirements with the alternative compliance pathway that credit EQpc114 Learning controls for thermal comfort provides.

As this alternative compliance pathway is not documented in much detail and also has never been discussed before in the LEEDuser forum, please provide your thoughts and professional opinions on the following approach.

The project has around 60,000m² (approx. 650,000 sqft) of open office space and at the same time the project is following a net zero energy (NZE) building approach.

The traditional way of addressing IEQc6.2 would consume a lot of energy by providing every second workstation with diffuser that has an adjustable airflow, due to the fact that a continuously high pressure needs to be maintained for all the diffusers.

In order to save energy, the ventilating system is controlled by sensor readings to supply pre-cooled fresh air only to spaces that exceed a threshold of 700 ppm carbon dioxide.

Also the open office is subdivided into many thermal zones that are each served by a dedicated fan coil unit (FCU) which just cools the air by recirculating it at very low speeds <0.15m/s (<30fps).

The granularity of these thermal zones exceeds the minimum requirements of ASHRAE 90.1, in order to provide cooling energy only to those areas that require for it. However, the zones are still big enough to accommodate approximately 10 workstations.

The temperature range for the interior space shall be initially from 21°C to 25°C (from 69.8°F to 77°F), but can be adjusted by the operator at any later stage, in order to fine-tune towards user comfort and NZE building approach simultaneously.

Alternative compliance pathway of EQpc114 Learning controls for thermal comfort shall be tread as followings:

Compliance with Option 1 of LEED BD+C v4 Thermal comfort credit is achieved, as the air speed is too slow to require for a local control of air speed (ASHRAE 55 – 2010 figure 5.2.3.2.).

An automated learning cooling system will be implemented which gathers the desired temperature from all computer workstations (approx. 10) in each thermal zone through a software application. Beside setting the desired temperature in this application each user will also receive information on the zone’s current temperature and the zone’s FCU set point.

This temperature set point for the FCU is controlled by the building management system (BMS) and the set point value shall represent the calculated average of all users’ desired temperature within the related thermal zone.

The BMS shall be enabled to benchmark each user temperature setting against the calculated set point in thermal zone where the user is located. This way the user’s satisfaction on thermal conditions can easily be rated: The bigger the difference the lower the user’s satisfaction.

Over time these real-time ratings will allow the operator to propose seating plan changes to the users according to their thermal preferences.

Simultaneously these seating plans will also allow the operator to reduce the energy demand of the building by fine-tuning the arrangement of thermal zones: It might be expected that people with thick clothing and/or preference on cool environments will sit close to cores, away from façades or on the North side of the floor plan. - Locations where thermal zones are probably maintained with lower energy demand.

On the other hand, people with preference on light clothing and/or warm environment might prefer zones close to façades on the East, South and West, as these zones usually require exponentially more cooling energy with lower temperature set-points.

The procedure for tracking shall include all the above data plus the energy demand on each FCU, subtotal cooling energy of each floor and the total cooling energy of the building in order to enable for reliable statistics and effective decision making during the operational fine-tuning. The data storage interval and storage period shall be hourly for at least 3 years.

The system’s essential feedback mechanisms inform each user

  1. In real-time at his workstation on the temperature set-point and current temperature in his’ zone, as mentioned above.
  2. On a monthly basis on opportunities to relocate/exchange his’ workplace towards a zone that better fits his’ personal preferences on clothing and thermal comfort, as mentioned above.

The plan for testing and repairing the devices and the system itself shall be developed together with the manufacturers and as part of the commissioning process.

I look forward to your comments.