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Winter to Spring - What It Means for IAQ, Energy Efficiency and Building Performance

Learn how the winter-to-spring transition affects indoor air quality (IAQ) and energy efficiency in commercial buildings. Explore seasonal challenges, cost impacts, and strategies for filtration, ventilation, and ESG performance.

Ava Montini

Mar 3, 2026

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The transition from winter to spring represents a notable shift in how buildings interact with their environment. While summer and winter tend to dominate operational planning, the periods in between often reveal the most about how systems perform.


During this seasonal change, outdoor temperatures fluctuate widely, and HVAC equipment may operate in both heating and cooling modes within the same week. At the same time, indoor environments are beginning to reflect new pressures: higher humidity, increased pollen levels, and shifts in outdoor particulate matter, all of which directly influence indoor air quality.


Unlike peak seasons, where energy demand is more predictable, the spring shoulder season creates variable conditions that highlight both strengths and weaknesses in building performance. This makes it a particularly relevant time to examine how ventilation strategies, filtration, humidity control, and monitoring systems function together.


Why the Transition Season Matters


During the winter months, most buildings are sealed tightly, which means indoor air is shaped mainly by what happens inside: CO₂ from people, plus everyday pollutants from activities and equipment.


As spring arrives, conditions change. Outdoor air becomes warmer and more humid. Pollen levels rise, and fine dust and particulates increase as the ground thaws and traffic increases. Bringing in more outdoor air during this time can help refresh indoor spaces, but it also means higher energy use to condition that air and the challenge of managing new contaminants.


This creates a tension between air quality and energy performance.


Without seasonal adjustment, several common issues emerge:


  1. System strain

HVAC equipment cycles on and off more often as outdoor temperatures swing, which can wear down components.


  1. Air quality drift

Pollen and particulates are more likely to slip indoors when filters aren’t adequate or properly maintained.


  1. Moisture buildup

Higher humidity increases the chance of mold or microbial growth in ducts and occupied spaces.


  1. Energy waste

Ventilation systems that aren’t tuned for the season often bring in more outside air than needed, raising utility costs.


Research from Lawrence Berkeley National Laboratory (LBNL) shows that economizers are improperly functioning in approximately 20–40% of commercial buildings, resulting in unnecessary energy use during the shoulder seasons.


U.S. DOE research shows that re-tuning building controls and HVAC sequences can reduce building energy use by more than 10 percent by correcting inefficient operations identified during mild weather transitions.


EPA and DOE modeling shows that increasing outside air flow without optimized controls can raise annual HVAC energy costs by approximately 2% to 18%, depending on climate and system configuration.


This translates directly into higher operating costs, elevated carbon intensity, and increased tenant complaints, particularly as occupants become more sensitive to air quality concerns.


What to Do Now?

The winter-to-spring transition acts as a natural diagnostic window. Variability reveals faults that may remain hidden during peak heating or cooling seasons.


Recommission Controls

Seasonal swings often expose calibration errors, damper malfunctions, and overridden sequences. Recommissioning projects have been shown to reduce building energy consumption by 10–20%, with typical measured savings in the 5–15% range and short payback periods of a few years.


Focus areas:

  • Temperature and humidity sensor calibration

  • Economizer functionality verification

  • Clearing manual overrides

  • Verifying demand-controlled ventilation (DCV) logic


Upgrade Filtration

Spring increases exposure to pollen, mold spores, and fine particulates. The U.S. Environmental Protection Agency recommends MERV-13 or higher filtration in commercial buildings where system design allows, citing measurable reductions in PM₂.₅ and improved occupant health outcomes.


Importantly, filtration upgrades must consider pressure drop. High-efficiency filters that significantly increase static pressure can elevate fan energy consumption and strain equipment. Low-pressure, high-efficiency filtration solutions help avoid this trade-off.


Optimize Ventilation Strategy

Outdoor air in spring can provide “free cooling” opportunities, but it can also carry pollutants and add to conditioning loads if not carefully managed. Economizers should be tuned for performance, and demand-controlled ventilation (DCV) should align intake with occupancy levels.


Field studies published in peer-reviewed journals have demonstrated that properly implemented demand-controlled ventilation (DCV) strategies can reduce ventilation-related energy consumption by up to 60% compared with traditional control approaches while maintaining indoor air quality.


Ventilation should respond to:

  • Occupancy (CO₂ levels)

  • Outdoor enthalpy conditions

  • Humidity thresholds


Manage Humidity

Relative humidity plays a major role in both comfort and health outcomes. ASHRAE and associated research show that maintaining indoor relative humidity between 40% and 60% corresponds with the least favorable survival conditions for microorganisms while also reducing symptoms of dry or irritated mucous membranes.


Spring often marks the point where latent load increases. Without monitoring, buildings drift into conditions that elevate mold risk and respiratory irritation.


Track IAQ in Real Time

Monitoring key indicators such as CO₂, PM₂.₅, and relative humidity provides a more accurate picture of performance than relying solely on tenant feedback. Real-time IAQ tracking reduces reliance on reactive tenant complaints and supports ESG reporting transparency. Increasingly, investors expect verifiable indoor environmental quality metrics alongside carbon reporting.


The Business Case

The winter-to-spring transition can carry financial implications beyond utility bills.


Short cycling accelerates compressor wear and reduces equipment lifespan. Poor humidity control increases duct and insulation degradation. Over-ventilation inflates both energy costs and Scope 2 carbon intensity.


CBRE’s 2025 Americas Office Occupier Sentiment Survey found that 37% of occupiers consider indoor air quality a key amenity that influences rent negotiations and leasing decisions, highlighting its role in tenant retention and satisfaction


For portfolio operators, shoulder season inefficiencies compound into:

  • Elevated summer demand charges

  • Higher carbon intensity metrics

  • Reduced mechanical lifespan

  • Increased unplanned maintenance


Spring performance is an early indicator of how well a building will handle peak-season demand. Addressing inefficiencies now protects both operating budgets and long-term capital planning.


The change from winter to spring can be a revealing period for building operations.


Buildings that respond intelligently to variability (balancing ventilation, filtration, humidity control, and energy optimization) reduce waste, improve indoor air quality, and protect long-term asset value.


The portfolios that treat the shoulder season as a diagnostic opportunity rather than a passive transition are better positioned for resilience, tenant retention, and ESG alignment.


Rather than viewing spring as a challenge, it can serve as a performance checkpoint. One that strengthens operational control before the demands of summer arrive.

Sustainability in Business: What Does it Mean?

  • Writer: Jennifer Crowley
    Jennifer Crowley
  • Aug 2, 2023
  • 3 min read

Updated: Jul 8, 2024

Five sets of hands donning business attire, overlapping hands with the top pair holding a mound of each which sprouts a green plant
Companies that think about the future and their broader impacts on society and the planet see tangible benefits.

What is a Sustainable Business?

A sustainable business, also known as a green or environmentally sustainable business, refers to an enterprise that operates in a manner that considers and minimizes its impact on the environment, society, and the economy. It is characterized by practices and strategies that integrate environmental and social considerations into its core operations and decision-making processes.


Here are some key characteristics and principles of a sustainability in business:

  1. Environmental Stewardship: A sustainable business takes proactive measures to minimize its negative environmental impact. This includes adopting energy-efficient practices, reducing greenhouse gas emissions, minimizing waste generation, promoting recycling and resource conservation, and using renewable resources whenever possible.

  2. Social Responsibility: A sustainable business recognizes its responsibility towards society and engages in ethical practices. It ensures fair treatment of employees, promotes diversity and inclusion, upholds human rights, and maintains safe and healthy working conditions. It also engages with local communities, supports social initiatives, and respects cultural diversity.

  3. Economic Viability: A sustainable business aims to achieve long-term economic viability while considering the environmental and social aspects. It seeks to strike a balance between profitability and responsible business practices. This involves incorporating sustainability into its business strategies, assessing and managing risks, and pursuing innovation and efficiency to create economic value.

  4. Stakeholder Engagement: Sustainable businesses actively engage with their stakeholders, including employees, customers, suppliers, local communities, and investors. They involve stakeholders in decision-making processes, listen to their concerns and feedback, and address their needs. This collaborative approach helps build trust, foster positive relationships, and align business goals with stakeholder expectations.

  5. Supply Chain Management: A sustainable business considers the sustainability performance of its supply chain. It seeks to work with suppliers that share similar values and adhere to environmental and social standards. This includes ensuring responsible sourcing, promoting fair trade practices, and supporting suppliers in improving their sustainability practices.

  6. Transparency and Reporting: A sustainable business embraces transparency by openly communicating its environmental and social performance to stakeholders. It may publish sustainability reports, disclose environmental impacts, and provide information about its sustainability goals, progress, and challenges. This promotes accountability and allows stakeholders to make informed decisions and evaluate the business’s sustainability performance.


Why sustainability is important?

A sustainable business plays a significant role in the environmental and social parts of society. Additionally, a business benefits both financially and socially from promoting sustainable efforts. Companies that think about the future and their broader impacts on society and the planet see tangible benefits. These include:

  1. Employees are increasingly looking for mission-driven, purpose-led employers who care about the planet when deciding where to work. 71% of employees and employment seekers say that environmentally sustainable companies are more attractive employers.

  2. Consumers are willing to pay a premium for goods from brands that are environmentally responsible. 80% of consumers indicate sustainability is essential to them.

  3. Governments, investors, employees, and customers are demanding new levels of enterprise accountability, including action to address climate change.

  4. Many of the world’s top economies have or are developing corporate disclosure requirements around environmental impact, driving businesses to curb GHG emissions.

  5. The rise of environmental, social and governance (ESG) investment criteria and sustainable investing means that a sustainable business is inherently more attractive to the rising numbers of responsible investors. Investment in ESG assets may reach USD 53 trillion by 2025, representing over a third of global assets.

Benefits of Sustainability in Business

Green graphic of sustainability images including plants, an organic green bin, EV and windmill with a backdrop of factories spewing smoke
Being known as a sustainable business can improve your brand awareness and help you attract consumers.

Investor appeal

4 out of 5 personal investors plan to act on sustainability or social responsibility factors in the next 12 months.


Increased longevity of transformation investments

The COVID-19 pandemic has accelerated digital transformation in most companies. If that transformation is sustainable, you’re building a more resilient business that is ready for disruption and new opportunities.


Competitive advantage

55% of consumers say environmental responsibility is very or significant when choosing a brand. Being known as a sustainable business can improve your brand awareness and help you attract consumers that are favourably predisposed to companies actively engaged in sustainable practices.


Talent acquisition

Employees seeking purpose-driven employment want to work for sustainable and socially responsible companies. By building a reputation as a sustainable business, you can attract and retain the right employees for your company.


Challenges with Sustainability in Business

  1. Cost – Implementing sustainable business practices typically requires higher upfront investments. In the short term, it will often be cheaper to stick with the status quo. Some organizations will need help building an investment case to show how immediate investment will result in more stable profitability over the long run.

  2. Supply chain inefficiency – Companies may lack the ability to implement sustainable solutions or even know where to start.

  3. Lack of expertise – Being unprepared to develop a corporate sustainability vision, strategy, and framework is a considerable risk. Every business needs an ecosystem of innovation partners to help them reinvent the world and create a sustainable future.

Explore expert insights, stay up-to-date with industry events, and gain a deeper understanding of the developments shaping the built environment.

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