It’s not something that you necessarily put your finger on. Sometimes, when you are inside, you are comfortable, yet on some occasions, you can feel that there is something wrong – you are too hot, or there is an unpleasant odour, or there is too much ambient noise. The difference is indoor environmental quality (IEQ).
What is IEQ?
IEQ is comprised of a combination and interaction among four main factors that affect health and comfort:
- Thermal comfort – the operative temperature that people experience. Importantly, this includes energy transfer that a person experiences via convection (air temperature), conduction (temperature or surfaces they physically are in contact with), and radiation (radiative energy transfer from surrounding surfaces). Upwards of 50 % of thermal comfort is comprised of the mean radiant temperature (MRT), which means that it is not enough to simply monitor and adjust air temperature, the MRT has to be accounted for.
- Indoor air quality (IAQ) – as the name suggests this is the standard of the air we breathe inside buildings. This is a complex issue, and governs the concentration of pollutants in the air (such as radon, carbon dioxide, ozone, etc.), as well as the bacterial load, and presence of pathogens or allergens.
- Visual comfort – all aspects pertaining to what and how occupants see, such as the colour and strength of lighting, the colour and design of walls, as well as views out of the building.
- Aural comfort – all aspects pertaining to what occupants have to hear, including ambient noise from outside the building, and noise levels inside from machines, people, the ventilation system, or any other source.
The interplay between these is complex. As Mudarri (1999) explains, “indoor environmental quality does not come in a can or a box, and you cannot order it by the ton or by the gallon. It has no clear definition or metric. Rather, it is wrapped into the fabric of the design, construction, operation, and maintenance of the building in hundreds of different ways.” Evidently, there is a lot to consider when it comes to IEQ.
However, there are clear cut ways to improve IEQ, which are explained below.
Why worry about IEQ?
Despite its complexity, IEQ is extremely important to get right. As I’ve covered in previous blogs, good IEQ corresponds to improved mental acuity, heightened productivity, and ultimately a comfortable and efficient workforce.
Essentially, good IEQ = high profitability. High impact, low cost.
Just because it is important, does not mean it has to cost you an arm and a leg to achieve good IEQ.
Here are just five ways that you can improve IEQ on a budget
- Use natural ventilation to improve IAQ. When it is possible (for small enough spaces, and in geographic locations with high quality outdoor air), natural ventilation can be used to augment or replace mechanical ventilation. Generally, issues of IAQ can be at least partially solved by increasing the ventilation rate, and increasing the proportion of ventilation air that is sourced directly from fresh, outdoor air. Natural ventilation can meet both of these goals, thereby improving IAQ and reducing the running costs of mechanical ventilation. Indeed, in international building codes designed to make buildings more sustainable (such as GreenMark, ASHRAE standard 90.1, and LEED), there is a large incentive to increase opportunities for and utilization of natural ventilation where possible to increase energy efficiency and reduce costs.
- Increase use of natural light. It has been shown that sufficient daylight in office workspaces improves IEQ by enhancing visual comfort. In turn, this serves to increase productivity, which will increase revenue over time. In the short term, using natural sources of light decreases the energetic consumption of artificial lighting, thereby saving money.
- Radiant sensible energy handling. Installing radiant cooling / heating systems is an excellent strategy for improving IEQ on a budget. The single largest factor that causes poor IEQ is thermal discomfort. Therefore, the primary avenue for ensuring good IEQ is excellent regulation of the thermal environment. Radiant cooling / heating systems monitor and regulate the operative temperature that a person experiences, factoring in the radiant heat that strongly contributes to a person’s thermal comfort, as explained above. HVAC systems such as conventional VAV systems that only monitor and regulate air temperature cannot achieve the same precise, even, and detailed regulation of the thermal environment. Therefore, radiant systems provide optimal thermal comfort. Moreover, radiant systems are silent, which significantly improves aural comfort. Radiant systems will therefore greatly improve IEQ. As for the low cost of this improvement, radiant systems have comparable initial installation costs to other sensible energy handling systems. If used in conjunction with a separate air handling unit (AHU) and latent energy handling system, such as a dedicated outdoor air system (DOAS), they have greatly reduced running costs compared to conventional all-air systems.
- Maintenance. Maintenance involves replacing or cleaning filters, cleaning HVAC ducting and vents, repainting, replacing defective light bulbs, among a host of other things. This is often area subjected to cutbacks, because the running costs and effort required for constant and high quality maintenance are not seen as worth the effort. The truth is quite the contrary. Good maintenance can not only greatly improve IEQ, it pays back the cost through improving comfort and health, as well as through increasing the lifespan and energy efficiency of equipment. According to Mudarri (1999), “a 30 per cent saving in HVAC energy and/or in HVAC maintenance translates into something of the order of $0.25–$0.35 per square foot. However, the 3 per cent loss in productivity associated with poor environmental quality would correspond to approximately $4.50–$6.00 per square foot, with unmeasured additional impacts of discomfort and poor health. From a holistic view this makes no sense – society is sacrificing values of over $4.50–$6.00 to gain values of $0.25–$0.35.”
- More control. It is important to note that IEQ can be improved simply by giving occupants more control to personally alter each component of their indoor environment as they see fit. Essentially, installing components that make it possible for occupants to open or close windows, adjust the temperature and light levels, or have control over what they listen to, can drastically improve their perception of the IEQ. Naturally, this raises issues when multiple people occupy a single space and do not all prefer the same conditions. This is therefore not always an applicable strategy, but if it can be implemented, it can be effective in cheaply improving perceived IEQ.
Each of these five strategies are good for improving IEQ at a low cost. However, it should be noted that investing more money in the short term to improve IEQ can save a lot of money in the long term. For example, increasing the ventilation rate of the HVAC system may cost more in terms of daily energy usage.
However, a higher ventilation rate (and therefore improved IAQ and comfort levels) will not only improve productivity, but also reduce absenteeism due to illness.
Another example is installing a “DOAS + Radiant” HVAC system. Retrofitting this system in an existing building may be seen as a high installation cost.
However, over time this system will save a large amount of money through its energy efficiency, as well as its accurate control of the thermal comfort and IAQ aspects of IEQ.
Therefore, the initial costs will quickly (typically in less than a year) be paid back, after which this system will provide good IEQ while simultaneously saving money. Overall, there are several cost effective ways to improve IEQ on a budget.
However, even if initial costs of improving IEQ are high, generally the returns afforded by having more productive staff, staff that are present more often, and staff that are not costing money because of visits to the doctor, will result in substantial financial advantages. As Mudarri (1999) put it, “the savings resulting from reduced maintenance or from energy conservation strategies are insignificant when compared to the potential health, comfort, and productivity losses of the occupants.”