COVID-19 and Building Ventilation

Keeping your HVAC breathing through the Covid-19 pandemic.

As the United States continues the fight against COVID-19 and many reopened businesses are concerned about indoor air quality, new requirements are being implemented for the public’s safety.

Recently, New York allowed for the reopening of shopping malls but with a mandate from Gov. Andrew Cuomo: Update HVAC filters with at least a MERV-11 rating to capture the potentially airborne coronavirus particles. Likewise, Colorado’s Denver Public Schools unanimously approved Denver schools to get ventilation upgrades to help stem the spread of coronavirus. So what do these guidelines mean, and could other states follow these policies?

HVAC Filters

Minimum Efficiency Reporting Value (MERV) is used to measure the effectiveness of air filters on a scale of 1 to 16. The higher the MERV rating, the greater the filtration, i.e. the smaller the particles it can catch. The Centers for Disease Control and Prevention (CDC) recommends to improve central air filtration to the MERV-13 level (or the highest compatible with the filter rack) and to seal edges of the filter to limit bypass.

MERV filter rating for HVAC systems
Model of MERV filter ratings. (Source)

However, updating an HVAC system’s air filters may not be as simple as it sounds. For instance, a common factor that will get overlooked is that most HVAC systems that were designed for lower MERV filters (likely most of them) will need to be rebalanced for the new filters. The higher the MERV rating, the better the filtration but also the higher the static pressure (or resistance) that the fan must work against, resulting in a drop in airflow. The reduced airflow could cause comfort problems and even frozen coils. To prevent these issues, the airflow will need to be measured with the new filters installed, and then the fan speed will need to be increased to achieve the designed airflow.

Yet this is still not a “one size fits all” solution for all. Many HVAC units cannot handle the higher-rated filters. Using a filter with a higher MERV rating may cause the motor to burn out. This is why it is important you have a trained technician review your unit before making any changes.

Other Building Ventilation Recommendations

In addition to replacing filters, ASHRAE recommends the following actions, with the ultimate goal being consistent and frequent air changes:

  • Increase outdoor air ventilation (use caution in highly polluted areas); with a lower population in the building, this increases the effective ventilation per person.
  • Open minimum outdoor air dampers, as high as 100%, thus eliminating recirculation. (During mild weather, thermal comfort or humidity within a facility normally wouldn’t be affected. During extreme weather, this clearly becomes more difficult to control.)
  • Consider portable room air cleaners with HEPA filters.
  • Consider Ultraviolet Germicidal Irradiation (UVGI), protecting occupants from radiation, which is particularly in high-risk spaces such as waiting rooms, prisons and shelters.

Developing Solutions

While the experts are recommending the above items, they are not mandatory across the country. States’ policies vary. Not to mention that COVID-19 research is still developing.

COVID-19 changing building ventilation

The result, in the near term, is likely to be a patchwork — some commercial buildings, schools, colleges, and other facilities will make investments, while others will not. One example of an organization making the investment to fight COVID-19 is KIPP DC, a publicly funded and privately operated network of seven school campuses with 1,200 employees and 7,000 students. KIPP DC has taken huge measures, working to find the ideal system optimized to filter the coronavirus.

KIPP DC’s Coronavirus Filter System (Source)

Hire Melink to Help

Overwhelmed and not sure where to begin? Melink employs a 100% self-performing, NEBB-Certified national network of Test and Balance (T&B) HVAC technicians that can quickly deploy to assess mechanical systems, verify airflow rates in accordance with ASHRAE 62.1 standards, and perform any traditional T&B work. 

We have multiple, long-standing relationships with some of the largest national restaurant, retail, hotel, and supermarket chains. These relationships began because those partners liked the idea of having just one third-party company to coordinate. Melink handles all their properties by objectively verifying that the HVAC systems were installed and are working as expected.

We are here to help you navigate the ever-changing recommendations and regulations of the pandemic. Let us help you keep your doors open while helping protect your employees, customers, and equipment. Contact us.

Prevent Sick Buildings: Why Positive Building Pressure Matters

Can a building get sick? I’ll give you the answer up front: Yes, sure, most definitely — a building can get “sick.” You may ponder… “But how can a building become sick? It is an inanimate object. It doesn’t live and breathe like humans!” On the contrary, your building is a living object. The main factor making your building come alive is its people: your customers, employees, and outside partners (think mail delivery or an overnight cleaning crew). Let’s dive into what factors can make a building sick and why maintaining positive building pressure is so important in prevention.

What Makes a Building Come Alive?

First, consider what may make your building come alive (or ultimately “infect” it):

  • Supplies
    The products you bring in (from any point of origin) may have outside contaminants or be perishable. As you know, perishables may emanate odors or fumes.
  • Chemicals
    You must account for chemicals or cleaning supplies in their controlled rooms (where exhaust is extremely important). 
  • Restrooms
    Consider the restroom facilities. Restrooms, especially those open to the general public (i.e. in a lobby area) can encounter high volumes of traffic and behaviors that may not meet sanitary standards. 
  • HVAC System(s)
    Your HVAC system is a key element bringing your building to life. With proper cleaning and maintenance, they are designed to provide comfort on demand. Heating and cooling are crucial amenities that have grown to be a must-have and are mandated by federal and local guidelines. 

When you take all these factors into account, it’s easier to understand how a building can become “sick.”

Sick Building Syndrome symptoms

Facility Managers: How to Prevent Sick Buildings

So how can a facility manager or building owner help to prevent sickness in a facility? As a professional in the HVAC industry, my primary goal is to earn your trust to maintain the wellness of your building’s HVAC system. Think about it — you can’t control others’ actions. There is no way to determine someone’s state of health as they are in your establishment. But you can control the HVAC system and make sure it is properly maintained to be a healthy system!

A little-known fact about HVAC systems that I will stress the importance: FRESH OUTSIDE AIR IS NEEDED TO MAINTAIN A POSITIVE BUILDING PRESSURE AT ALL TIMES. What does this mean, and why is it important?

  1.  Your restaurant, retail store or office building, has many moving parts to bring it alive, has to breathe. Like any living thing, it requires oxygen to replace the carbon dioxide. The equation should result in bringing in a greater amount of fresh air than the carbon dioxide, chemicals, fumes/odors, and cooking effluents that the building creates. When this happens, there should be a slight positive pressure from the inside of your establishment that pushes outward at your doors and drive-thru windows.  A proper HVAC test and balance (TAB) by an NEBB-Certified firm like Melink can help you achieve this goal.  

  2. A common oversight that people make is assuming, “My building is positive. We’re in good shape.” But how sure are they that the lungs of the HVAC system are clean and free of operational damages? Many times, I have encountered damaged and clogged filtration components within an HVAC system that may lead to costly repairs to your equipment and structural damages:
  • Clogged or missing outside air intake filters
  • Clogged, missing or inadequate air filters
  • Clogged evaporator and condenser coils
  • Clogged and inadequate fan blower wheels
  • Mold and mildew
  • Trapped small animals that lead to contaminations
  • Contaminated duct work that eventually shows up on the supply, return and exhaust grilles throughout the establishment 
Checking HVAC ductwork for positive building pressure

All these issues work together to create a sick building.  The opposite of positive pressure is that dreaded negative pressure. Every time your facility’s doors open, all of the outside air conditions are sucked into the building.  These elements can be hot or cold air, humidity, airborne pathogens, and odors. The humidity attaches to the chilled supply diffusers and grilles, creating moisture buildup that drips onto your floors, tables, customers, and clients.

Checking HVAC filters for positive building pressure

Of course, it’s not feasible for a facility manager to know the ins and outs of every HVAC system of every facility he/she manages. So let us do the work for you! Melink Corporation’s T&B technicians can be your eyes and ears to help your facilities maintain positive building pressure. We are an army of application engineers with skilled LEED and NEBB certifications. Our company is nationwide and has more than 30 years of experience. Along with services that will help you on your way to a healthy building, we offer a monitoring system and demand ventilation systems that will alert you when problems or concerns arise.  These services, along with reliable routine maintenance will minimize uninterrupted service to your most important people. We can help you protect your customers, employees, and outside partners from sick buildings.

Coronavirus & Indoor Air Quality

Now, maybe more than ever, many businesses are concerned about indoor air quality (IAQ) to protect employees and customers from coronavirus. With the current spread of COVID-19 across the globe, it is important that we are all taking the necessary steps to reduce the spread of the virus. As part of this, it is important to recognize how your HVAC system can impact your IAQ during long hours of social distancing, as well as steps that can be taken to limit the spread of the virus in buildings.

In a normal year, the typical American spends 90% of his or her time indoors. With current guidelines about social distancing, this number is expected to increase over the next few months. Prior to recent events, the American Medical Association stated they believe 50% of illnesses are caused, or aggravated, by polluted indoor air. Furthermore, per the EPA, indoor air contains two to five times more pollutants than typical outside air.

Coronavirus
Source: Centers for Disease Control and Prevention

So what does this mean for the COVID-19 crisis? Now that we have learned the novel coronavirus can be spread via airborne transmission when in close contact, there is the possibility that the HVAC system could cross-contaminate. That means air from an infected person could recirculate through a facility’s HVAC system and infect another individual. An example of this is how cruise ships experienced severe outbreaks. All cabins share an HVAC system, which is working as a mode of transmission from one individual to another.

While this risk of shared indoor air cannot be completely eliminated, there are a few items that can be addressed to reduce the potential for transmission through the HVAC system including:

  • Enhanced Ventilation & Ventilation Effectiveness
  • Source Separation
  • Air Filtration
  • Operable Windows

First and foremost, facilities should ensure their HVAC equipment is bringing in the correct amount of outside air required by the engineered designed plans, as well as managing the pollution and exhaust from your building properly. To further mitigate this risk, one should attempt to increase the percentage of outside air being brought into a facility to a higher percentage than minimally specified. In doing this, the equipment will reduce the amount of air being recirculated through a building. This will not only reduce “shared air,” but will also decrease levels of CO2 and other indoor air pollutants that can create an uncomfortable, or unhealthy, facility.

For a residential facility, where air source isn’t as easily controlled, it can also be helpful to open windows to bring in fresh air to any given room. In addition, it is worth verifying that any fresh air being brought in is being evenly distributed. If it isn’t, certain rooms may have less air turnover, meaning that the air isn’t circulating in and out of the facility properly.

The next few months may be difficult with longer hours than normal spent indoors. It is important that we are all taking steps to minimize the spread of coronavirus and other airborne illnesses both now and in the future. Melink offers products and services specifically designed to track, trend, and improve indoor air quality. Click to learn more about our HVAC test and balance services or PositiV® building health monitor, or contact us today. Our techs are the certified pros in indoor air quality — let us help you mitigate your risk while protecting employee and customer wellness.

R-22 Refrigerant (Freon) Is Obsolete: What Next?

The United States has slowly been phasing out the use of R-22 refrigerant (or Freon), a Hydrochlorofluorocarbon (HCFC) refrigerant found in older commercial and residential HVAC equipment.

Commonly used in roof top units (RTUs) and split systems,  R-22 and other HCFC refrigerants are known to deplete the Earth’s protective ozone layer and contribute to harmful climate change.

To combat this, the U.S. has slowly been phasing out the use of R-22 refrigerant, per the following phase-out schedule:

  • 1/1/2010: The U.S. government bans the use of R-22 in new HVAC equipment.
  • 1/1/2015: The U.S. government bans the production and import of all R-22.
  • 1/1/2020: The U.S. government bans the use of all R-22 (with a few exceptions).  Only expensive, reclaimed R-22 can be used for repair of older R-22 equipment.  Effectively, this is the end of the road for R-22 use in the U.S.

How does the 2020 R-22 refrigerant ban affect my facility? 

  • The cost to repair older R-22 units is now skyrocketing and is usually cost-prohibitive.
  • R-22 costs per pound have risen approximately 500% in the past five years — up to 12 times the cost of modern-day, more ozone-friendly refrigerants.
  • Older R-22 units have much lower Energy Efficiency Ratio (EER) ratings and are as much as 50% less efficient than current-day, high-efficiency units. 
  • In most cases, older R-22 RTUs cannot be converted to R410A refrigerant. These older units will need to be replaced with RTUs that are more energy efficient and more environmentally friendly. 
  • Emergency replacement, AKA “Fix-on-fail,” is the costliest way to repair older R-22 units. In fact, this philosophy is around 70% more expensive per unit than a proactive roof-sweep or planned equipment replacement program.

So what should I do now, and where should I start? 

First, to really understand how the R-22 ban affects your business, I recommend companies start with an HVAC inventory. Conduct a detailed survey of all facilities to verify the age and condition of all HVAC equipment, including newer and older HVAC units.

Secondly, I recommend involving a national or regional HVAC installation partner, as well as an independent national testing, balancing and commissioning partner such as Melink Corporation to provide the unit data and a complete assessment of the entire mechanical system. (Check out these tips for hiring a Test & Balance partner).

Ideally, the assessment should include the following:

  • Duct-work inspections
  • RTU and exhaust fan inspections
  • Airflow measurements to verify proper building airflows and to identify existing air-balance issues

If the entire HVAC system is not inspected, the building will often continue to have comfort problems and building balance issues, even after the new equipment is installed. Without a thorough inspection, the positive effects of the new, energy-efficient (and R-22 refrigerant ban-compliant) HVAC equipment will not be fully realized, resulting in a lower-than-expected ROI.

For further information on HVAC surveys and other custom scopes of work, please e-mail [email protected] or call at (513) 965.7300.

Sources:
Air Conditioner Refrigerant Costs — On The Rise? (Fixd Repair)
What Is the #1 Way to Save Money on Your Rooftop Unit? (U.S. Department of Energy, Office of Energy Efficiency & Renewable Energy)

PositiV and Test and Balance: A one-two punch to sick building syndrome

Sick building syndrome is a condition that affects a building’s occupant due to unhealthy factors in the work environment primarily associated with poor ventilation and airflow in the facility. Per the EPA, symptoms of Sick Building syndrome include acute discomfort such as headaches, dry skin, coughing, dizziness, and nausea. Despite all these symptoms Sick Building syndrome can go undetected for years as the symptoms are all relatively minor and occur over multiple years.

With the release of Melink PositiV™ earlier this year, facility managers can now remotely diagnose and asses 4 of the key building metrics that contribute to building health. These include CO2, relative humidity, building pressure, and temperature. By ensuring these 4-building metrics are within acceptable ranges facility managers can sleep well knowing that they will be able to monitor and track if their facility is showing early signs of sick building syndrome. This can empower the end user to act and stop the early patterns that can lead to numerous issues down the road.

You know it is time to act when one of the 4 measurements are outside of the recommended limits. A primary way of attempting to correct any of these issues in a facility is to have a test and balance to reset airflow to the engineered design plans. During a test and balance, existing issues are identified and corrected to allow for proper airflow into the space. Through this process the technician should be examining and resetting the outside air dampers at the facility to allow the building to receive the correct amount of fresh air. The combination of monitoring and acting on the data allows end-users to ensure comfortable, healthy and energy efficient facilities.

Why Recommission?

Building commissioning is often viewed as a one-time procedure performed during a building’s initial construction, among hundreds of other tasks.  (That is, if commissioning was even performed at all… which is another topic in itself!)  An investment was made into ensuring that the newly constructed systems were indeed installed correctly and operating properly.  So then, if a building was already commissioned, why would you want to recommission it?

Before answering that, we should first define what recommissioning is.  Simply put, recommissioning is a process that helps get a building back to the operational performance that was intended from the initial design and construction.  It’s much like a tune-up for your car.  Commissioning occurs during the design and construction of a building.  Add the “re” to commissioning, and it implies that you are “commissioning again” an existing building that was previously commissioned.  In a similar way, when you add “retro” to commissioning, it implies that you are “going back and commissioning” an existing building that was never commissioned before.  According to the Building Efficiency Initiative, “it can often resolve problems that occurred during design or construction, or address problems that have developed throughout the building’s life as equipment has aged, or as building usage has changed.”

Recommissioning is often and best done on a planned, recurring basis.  This is because buildings change over time.  Just because a building’s systems were optimized when it was first commissioned, doesn’t mean they will stay that way forever.  As with most things, building systems wear and their performance degrades over time.  For example, a building may undergo a remodel or the way its space is used may change, pieces of equipment fail and are replaced, control setpoints are tampered with, and sensors fall out of calibration.  Recommissioning can help to diagnose the source of issues and identify building systems that have drifted, leading to higher energy costs and other negative side-effects.  Such issues include duct air leakage, HVAC and lighting left on while a space is unoccupied, airflow not balanced, dampers and economizers not working properly, improper setup or failure of controls, and much more.

Identifying and correcting these issues through a recommissioning process will lead to significant energy savings.  According to a report by Lawrence Berkeley National Laboratory, commissioning produced 16% median energy savings in existing buildings with a payback time of 1.1 years.  Furthermore, recommissioning results in a healthier and more comfortable environment for the building occupants, which is not as easy to quantify as energy savings but is even more impactful to an organization’s success.

TOP 3 Points to Consider Before Scheduling an HVAC Balance

There are a few important items that you want to take into account before you schedule an HVAC balance. While these 3 points may seem obvious, there are many instances where a technician gets onsite and the job-site isn’t ready or they can’t access areas that they need. These tips can save time and money for everyone!

1. HVAC equipment is installed and operational.

This one seems like a no-brainer! However, there are always occurrences when a technician arrives onsite to perform a balance and necessary equipment either hasn’t been installed or isn’t properly operational. Examples include VAV’s or dampers that haven’t been installed, or a RTU that isn’t operational.

Ensuring that all ductwork has been completed, balancing dampers are properly installed, any grilles, registers and diffusers are installed, and the RTUs have clean filters helps make sure a technician can provide a proper air balance, as well as mitigate any potential return service costs. Making sure that all equipment (especially RTUs) has undergone a proper start-up to confirm power should always be completed ahead of Melink’s arrival.

2. All HVAC equipment can be easily accessed by a technician.

Another hindrance to any proper test & balance is not being able to access the necessary equipment. This includes equipment installed inside the building, as well as equipment on the roof. When working with a customer located inside a mall or shopping center, security and approved roof access becomes another added component.

Melink typically requires assured access to all applicable HVAC system equipment, including RTUs, VAVs, Exhaust Fans, dampers, etc. Access to fully open dampers, ceiling-height diffusers, and thermostats that may be in an office is necessary to properly complete the balance. Our Account Coordinators will also discuss roof access, security measures, and accessibility to ladders or lifts.

3. Allotting adequate time (2-3 weeks) to schedule and complete the balance.

Though some seasons are busier (or slower) than others, our goal at Melink is to provide every customer the same level of service excellence no matter the time of year. This includes communication with the customer, scheduling the site visit with one of our National Network technicians, performing the balance and working with the customer on any punch-list items, and finally, providing a certified test & balance report.

Our team of National Account representatives and technicians work with the customer through each step of the process. Scheduling an HVAC balance with Melink approximately 2-3 weeks out from turnover will help to ensure a proper and complete balance. It also allows enough time to work through any punch-list items or lingering comfort issues for the customer.

National and Independent Test and Balance: We Go Where You Are!

National retailers, restaurant chains and commercial property groups all have similar HVAC needs all across the country.  When going to a Starbucks and asking for a “Grande Pike”, we have a set expectation of what we will experience when the barista delivers that 16 oz cup of perfection, right?  Why should commercial buildings be any different?  Don’t the brand managers and facilities teams want their building occupants to have the same, consistent comfortable, healthy experience when inside of their buildings?  Don’t they want their customers and employees to enjoy a safe, comfortable, energy efficient indoor environment at every location nation-wide?  We find the answer to be a resounding YES!

In 1987, founder Steve Melink saw the need for consistent, national, test, balance and commissioning services for national restaurant and retail chains.  While test and balance companies weren’t new, there was no one fulfilling the services in an unwavering manner across the entire nation. Companies either performed work in a small region, or they hired out whomever they could find across the country as jobs popped up. This not only left varying and unreliable reports, but also no standard across the nation for larger national accounts. What was done at one location, may have been measured differently at another, or not even checked at all! Steve understood the need for one company to be able to deliver reliable and consistent services and reports to all business, regardless of location.

13,000+ projects completed since 2014!!

Fast forward 32 years.  Today Melink Corporation is still known as the standard for national test, balance and commissioning services and serves many of the world’s largest and fastest growing restaurant and retail chains.  In the same vein as the Starbucks example, our customers expect consistency and quality no matter where they are building and remodeling.  We don’t leave our quality to chance or to the general contractor’s sub, we hire and train the best technicians and engineers.

With our 100% self-performing, independent, national team of Test, Balance and Commissioning professionals, Melink takes our quality on the road, each and every day.  Simply put “We Go Where You Are”!

Are you struggling to find someone that can service any of your locations? Contact our team by phone at 877-477-4190 (toll-free) or online at [email protected] or here…we look forward to helping find a solution for your business!

When Should My Building Be Balanced?

A proper air balance within a building is an important factor for providing a healthy and comfortable indoor environment for occupants.  Like many other critical building systems, the air balance must be maintained over time, and isn’t something that you can simply “set and forget”.  So then, when should a building be balanced?  Here are some common events that would trigger the need to perform an air balance.

New Construction:

Every building that has some form of HVAC system (heating, ventilation, and air conditioning) should be balanced when it is first constructed. By this, I mean that the HVAC systems should be inspected, tested, and adjusted to ensure that they are operating correctly, efficiently, and as intended by the design engineer and as expected by the building owner. A balanced building will provide a comfortable and healthy indoor environment for the occupants, delivered in an energy efficient manner, and will have a proper positive pressure. Select a TAB professional to perform the air balance who is objective, meaning that they are hired directly by the building owner and are independent of the installing contractors and equipment manufacturers, who is experienced in your particular type of building and HVAC systems, and who is certified by an industry-recognized accrediting agency, like NEBB or AABC.

Remodel:

The building should be rebalanced during any major remodel event, such as expanding the building or changing the functional use of a space within the building. This is important because the HVAC system was originally designed and balanced for specific use conditions, and when those conditions change, the system will need to be readjusted. Be sure to consult with your mechanical design engineer prior to the remodel to verify that the existing HVAC system can handle the new demands. The building should also be rebalanced anytime elements of the HVAC system are modified or replaced, such as when ductwork is rerouted or when aged equipment is upgraded. This is important for verifying that the new equipment is installed correctly, operates properly, and is adjusted for the design conditions. For a building that has cooking operations, it is important to also rebalance whenever the cooking appliances are relocated or replaced with equipment of different use or heat load, such as replacing an oven with a fryer. This is significant because a kitchen ventilation system is designed for a specific bank of appliances. When the appliances and cooking operations change, the ventilation system will need to be adjusted to ensure it correctly captures and contains the heat and effluent produced.

Periodic Tune-up:

Even if a building has been balanced during the original construction, and it is not undergoing any remodels or equipment replacements, it should still be rebalanced periodically. This is because the performance of the HVAC system can change over time due to normal use and wear and also due to adjustments made by operations and maintenance personnel. Examples of this are when an operator switches the fan mode of the thermostats from ON to AUTO or when a service technician closes the outside air dampers in a rooftop unit in an attempt to fix a comfort complaint. For the complete building HVAC system, I would recommend a proactive rebalance frequency of every two to three years. This will ensure that the systems operate effectively and efficiently throughout their lifecycle and will help prevent the very costly issues created by having a building out of balance for a prolonged period of time.

Want to understand more about air balances? Read about air balance basics for existing facilities, watch our video on how an air balance works, or contact us to learn more!

Stay Ahead of HVAC Problems this Spring

While many are excited to emerge from a long and cold winter and enjoy the rising temperatures that come with spring, not everyone loves the shift in seasons. Facility managers around the country dread the season change as it always brings lingering HVAC problems to the forefront. Every year during the spring and fall as temperatures are changing, buildings around the country work hard to adjust to the change in seasons as well. The HVAC systems go from cold temps outside and constant heating of the building to cooling instead, or vice versa. This dramatic change takes a toll on the building envelope and interior and can make underlying HVAC problems that went unnoticed during one season, suddenly very noticeable. Employees and paying customers alike are feeling the discomfort of hot and cold spots, condensation dripping, A/C not kicking on correctly, doors blowing open, and other annoyances.

These types of issues not only affect the comfort for your customers in the facility, they can also lead to long term maintenance and higher energy costs should they not be fixed quickly. This is where having an independent 3rd party onsite to inspect the equipment can assist. Hiring an independent company can help in identifying the underlying cause of such problems and repair minor issues that may have gone undetected for years. By having the facility inspected by a truly independent company, facility managers can know that the information they are receiving provides a truly accurate snapshot of their facility and is not biased or swayed based on loyalties. You will get real results with accurate and actionable information.

If you are experiencing any of these issues with the upcoming season change, it is recommended to have these issues investigated immediately. Prices begin to rise just as the temperature does in the summer, as construction demand is at its peak during this time. Seeing some of these issues in your building? Contact us here to talk with our team about ways to get in front of problems before they get worse!