What We’re Doing on Energy and Health at the Distillery North

By Fred Gordon, founder and President of Second Street Associates

The Distillery North, completed in 2017, was the first multi-family Passive House (PH) building in Massachusetts. It demonstrated that Passive House buildings, which typically cost only slightly more than ordinary buildings to construct, can reduce all energy use dramatically compared with non-Passive House new buildings, including those built to the LEED standard. As you can see below, the Distillery North (represented by the green line on the far left) uses 63% less energy than code-compliant and LEED-certified multi-family buildings built in Boston in 2020.

Energy reduction for heating and cooling alone, while hard to break out precisely from total energy costs, is reduced by 80% to 90% below the comps. The Distillery North is still the most energy efficient multi-family building in Boston, and as of 2022 was performing better than comparison buildings in Philadelphia and New Hampshire (read the details of that comparison study here).

The Distillery North was an important boost to encourage other low energy buildings in Massachusetts, several of whose designers and builders came out of our project. As of 2020, the Distillery North was still the only multi-family Passive House development in Massachusetts. As of 2022, an additional 135 buildings were in design or construction. Today there are 141 more Passive House buildings with 8,500 units in the pipeline.

What we’re doing to make this building better: ventilation

The big revolution in building design comes from the recognition of the importance of ventilation. Ventilation is important for building energy performance. And it is important for health. And the two are intertwined. In the Distillery North, we have been pioneers in ventilation and we continue to implement improvements which are unique in building design.

Ventilation and energy performance

For a building to have efficient heating and cooling, it must be tight. Otherwise, the heat or coolness you put into it leaks out – you are heating or cooling the outside. To achieve its stringent energy goals, Passive House requires that leakage through the walls must be extremely low: .6 air changes per hour (ACH) at 50 pascals of pressure.

But for people to breathe, buildings need fresh air. Passive House buildings therefore use a Heat Recovery Ventilator to introduce fresh air but without losing the building’s heat or cool from air conditioning. Passive House buildings can be ventilated without losing a significant amount of the heat or coolth that you put in. With that design, and adequate insulation, our Passive House building reduces the heating and cooling loads by 80-90% relative to the average American building.

Most American buildings don’t know how to do this. They fail to be energy efficient, and they also fail at ventilation. Old buildings often have no fresh air ventilation at all, but depend upon the air blowing in through the building’s walls; or else they have exhaust fans in the kitchens and bathrooms which blow out the stale air, and this increases even more outside air through the walls, carrying mold and off-gassing from toxic building materials. Most homes are for that reason both polluted and inefficient. We solve these problems.

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Ty Newell of Build Equinox overseeing the install of a CERV2 in owner Fred Gordon’s apartment.

Ventilation and indoor air quality

A building must be energy efficient and manage pollution at the same time. Air that is sucked in through the wall cavity is not good for people. The worst pollutants are microparticles which are small enough (smaller than 2.5 microns) to pass through the lungs. In the body, they are associated with dementia, cancer, autoimmune disease, heart disease, birth defects, and mortality.

This air pollution can come from outdoors, but is also often generated inside the living space by cooking and the off-gassing of building materials, cleaning agents, and candles. A good building must prevent bad air from coming in, but must get rid of the pollution that is generated indoors. We aim to do both.

Recent research from the Harvard Chan School of Public Health also indicates that microparticles can enter the brain by breathing through the nose. The olfactory sensors in the nose are directly connected to the brain, and this intensifies the danger of brain inflammation which is associated with dementia.

The average level of PM 2.5 in the Distillery North apartments—using my own living unit as standard—from January to November 2023 is 5.7 micrograms per cubic meter of air (µg/m3), and this includes the periods of increased smoke pollution from the Canadian wildfires. More typical is the average reading of 3.2 µg/m3, as measured from October 16 to November 15, 2023. This contrasts with a much higher level in the average American home.

Passive House greatly reduces the presence of microparticles in indoor air. The upper limit for airborne PM 2.5 allowed by the Centers for Disease Control (CDC) is 9 (µg/m3), a standard also stipulated by the World Health Organization (WHO).

Our plan is to cut microparticles yet further by dealing with both the microparticles from cooking and microparticles during the weeks of wildfires which are expected again this summer. Wildfire smoke causes serious damage, especially to the lungs of young children. We expect to drive microparticles down to a level of 3.2 µg/m3, which is about ¼ of what is outside.

Ventilation and preventing the spread of contagious diseases

COVID, RSV, and flu spread mainly because ventilation rates are inadequate. The new equipment that we are installing, the CERV2 by Build Equinox, increases ventilation rates 2.5 times over the ventilation equipment we have been using. It is still possible to get COVID in such a living place, but the rate of transfer is reduced to such an extent that the rate of extinction exceeds the rate of spread. That means that with the sort of equipment that we’re installing, diseases like COVID would self-extinguish.

The Center for Disease Control and ASHRAE (the body that defines engineering standards) have both recognized that the existing ventilation rates are inadequate to stop the spread of COVID. They have therefore increased required ventilation to control these epidemics. The equipment that we are installing and testing (CERV2) meets both of the CDC and ASHRAE standards. We are the first residential building in the country to meet the new ASHRAE 141 requirement.

The CERV2 units we are testing are also equipped with UV light systems that kill viruses and bacteria, further reducing the spread of disease. Further, when the ventilation is adequate, as measured by the concentrations of CO2, the machine goes into a recycle mode, which brings interior air repeatedly through very high effectiveness filters. This further drives down the concentration of infectious agents.

The benefits of ventilation on cognitive performance by controlling CO2 levels

When there are a lot of people in a living space, CO2 levels rise. Recent research has shown that this results in a dramatic decline in people’s cognitive capacity. The CERV2, besides dealing with energy pollution and infectious diseases, also controls CO2.

Research from Harvard’s Chan School of Public Health shows that CO2 (the product of people’s breathing) at levels which are typical indoors when there is a social gathering, causes a decline in cognitive performance. Control of CO2 levels, which is already being implemented in office settings because of its measurable effects on productivity has not yet been widely implemented in residences. The problem is not just a matter of stuffiness; at levels of 1400 parts per million (PPM), basic decision making is reduced by 25% and strategic thinking by 50%.

With the CERV2, we have been able to keep CO2 to an average of 521 PPM with a maximum of 636. It does this through the efficiency of the equipment itself, and also the fact that its ventilation is demand-driven (as opposed to constant flow). When there are few or no people in the space, the CERV2 goes into a recycle mode and drives interior air repeatedly through its filters. This continues to raise interior air quality, but without the cost of bringing in unconditioned air. The CERV2 makes it possible to have good ventilation and low energy simultaneously.

What is revolutionary about the innovations in this building

The existing Passive House building is better than any other building around for both energy efficiency and health. We are working now to make it even better. The CERV2, which we’re installing in selected units, is able to meet more demanding air ventilation standards, which improves air quality, impedes disease spread, and improves mental functioning. Further, it brings these benefits without using more energy than a regular Passive House, which is already the most efficient building out there. That is what we are doing here.