IES Consulting performed a comfort assessment for WELL Building Standard credit 76 on this renovated 40,000 m2 office development at 21-27 rue Philibert Delorme, Paris. IES performed an annual energy simulation to test the building and its systems could comply with ASHRAE Standard 55-2013 and demonstrate potential for the building to meet the required criteria, section 5.3.2 the ‘Analytical Comfort Zone Method’. The building is conditioned by fan coils and also includes the renovation of an auditorium and a restaurant business.
The assessment sought to demonstrate whether the building could maintain comfort levels of a Predicted Mean Vote (PMV) between -0.5 and +0.5. Within this range is considered comfortable where less than 10% of occupants would be dissatisfied with the internal environmental conditions.
Occupancy comfort is affected by a number of factors; including activity level, clothing Level, local air velocity, dry bulb temperature, mean radiant temperature and relative humidity.
The VE model was configured to represent the HVAC systems and mimic the available heating and cooling capacity. The HVAC systems were controlled to try and maintain the zones within an operative temperature inside the comfort range appropriate for the activity and clothing levels for each space.
The final modelling predicted that all spaces within the building would achieve the PMV comfort criteria except for the Café space which had only 2 hours outside of the PMV band on the cool side. These 2 hours equated to less than 0.5% of the occupied time, which in comfort terms is almost insignificant. The cause was attributed to the low mean radiant temperature experienced from the glass surfaces bounding the Café. The project is currently under consideration for WELL approval.
Operative temperature itself is a good metric for determining comfort and is formed from both air temperature and mean radiant temperature. This is significant in spaces where at times these two environmental components differ significantly, case in point are zones with large amounts of glazing.
In the winter months, due to the higher U-value associated with glass, the inside surface will typically have a lower surface temperature than nearby opaque surfaces. Where there is a large proportion of glazing this can result in a low mean radiant temperature. In order to compensate for this and achieve a comfortable operative temperature then the air temperature needs to be elevated.
Conversely during times of significant solar load, the mean radiant temperature can be high and to maintain a comfortable operative temperature the space air temperature needs to be lowered to compensate.
WELL Credit 76 Thermal Comfort
Thermal comfort in the body is provided through homeothermy, the balancing of heat gains and losses to maintain the body’s core temperature within its narrow range, 36-38 °C [97-100 °F], and regulated by the hypothalamus. Thermal comfort can affect mood, performance and productivity. However, temperature preferences are highly personal and differ from one individual to another. Balancing the energy requirements of large buildings with the varied occupant preferences can thus be challenging.
This feature uses best practices to ensure a sufficient level of comfort for the majority of occupants. ASHRAE Standard 55 specifies that thermal comfort can be achieved in two ways, either through the Standard Comfort Zone or the Adaptive Comfort Zone.
Part 1: Ventilated Thermal Environment
All spaces in mechanically-ventilated projects meet the design, operating and performance criteria:
a. 92 ASHRAE Standard 55-2013 Section 5.3, Standard Comfort Zone Compliance.
Part 2: Natural Thermal Adaptation
All spaces in naturally-ventilated projects meet the following criteria:
a. 92 ASHRAE Standard 55-2013 Section 5.4, Adaptive Comfort Model